U.S. patent application number 11/210019 was filed with the patent office on 2006-09-14 for standard for referencing luminescence signals.
Invention is credited to Doris Ehrt, Axel Engel, Rainer Haspel, Joseph S. Hayden, Katrin Hoffmann, Uwe Kolberg, Ute Resch-Genger, Michael Stelzl.
Application Number | 20060202118 11/210019 |
Document ID | / |
Family ID | 36405945 |
Filed Date | 2006-09-14 |
United States Patent
Application |
20060202118 |
Kind Code |
A1 |
Engel; Axel ; et
al. |
September 14, 2006 |
Standard for referencing luminescence signals
Abstract
The invention discloses a standard for referencing luminescence
signals, having an optically transparent base material comprising a
lanthanum phosphate glass, a fluorophosphate glass, a fluor-crown
glass, a lanthanum glass, a glass-ceramic formed therefrom or a
lithium aluminosilicate glass-ceramic, the base material including
a bulk doping with at least one constituent which is luminescent
and comprises at least one rare earth and/or a nonferrous metal, in
particular cobalt, chromium or manganese.
Inventors: |
Engel; Axel; (Ingelheim,
DE) ; Haspel; Rainer; (Monsheim, DE) ;
Resch-Genger; Ute; (Berlin, DE) ; Hoffmann;
Katrin; (Berlin, DE) ; Ehrt; Doris; (Jena,
DE) ; Kolberg; Uwe; (Mainz, DE) ; Hayden;
Joseph S.; (Clarks Summit, PA) ; Stelzl; Michael;
(Mainz, DE) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Family ID: |
36405945 |
Appl. No.: |
11/210019 |
Filed: |
August 23, 2005 |
Current U.S.
Class: |
250/252.1 ;
250/483.1 |
Current CPC
Class: |
G01N 21/278 20130101;
G01N 2021/6495 20130101; G01N 2201/13 20130101; G01N 21/6452
20130101 |
Class at
Publication: |
250/252.1 ;
250/483.1 |
International
Class: |
G01D 18/00 20060101
G01D018/00; G01N 21/64 20060101 G01N021/64 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 25, 2005 |
DE |
10 2005 010 774.5 |
Claims
1. A standard for referencing luminescence signals, comprising an
optically transparent base material, said base material being
selected from the group formed by a lanthanum phosphate glass, a
fluorophosphate glass, a fluor-crown glass, a lanthanum glass, a
glass-ceramic formed from a lanthanum phosphate glass, a
glass-ceramic formed from a lanthanum glass, a glass-ceramic formed
from a fluorophosphate glass and a lithium aluminosilicate
glass-ceramic; said base material further comprising a bulk doping
with at least one luminescent component selected from the group
formed by a rare earth and a nonferrous metal.
2. The standard of claim 1, wherein said bulk doping comprises 0.01
to 5% by weight of at least one dopant selected from the group
formed by Cr.sub.2O.sub.3, Ce.sub.2O.sub.3, Eu.sub.2O.sub.3,
Tb.sub.2O.sub.3, Er.sub.2O.sub.3 and Tm.sub.2O.sub.3.
3. The standard of claim 1, wherein said bulk doping comprises at
least one component selected from the group formed by cobalt,
chromium and manganese.
4. The standard of claim 1, wherein said base material is a
lanthanum phosphate glass comprising (in wt.-% based on oxide
content): TABLE-US-00003 P.sub.2O.sub.5 30 to 90 La.sub.2O.sub.3 0
to 30 Al.sub.2O.sub.3 0 to 20 R.sub.2O 1 to 20 refining agents 0 to
3,
wherein R is at least one element selected from the group formed by
the alkali metals.
5. The standard of claim 4, wherein said base material is a
lanthanum phosphate glass comprising (in wt.-% based on oxide
content): TABLE-US-00004 P.sub.2O.sub.5 50 to 80 La.sub.2O.sub.3 5
to 20 Al.sub.2O.sub.3 5 to 15 R.sub.2O 1 to 20 refining agents 0 to
3,
wherein R is at least one element selected from the group formed by
the alkali metals.
6. The standard of claim 5, wherein said base material comprises 5
to 15% by weight of K.sub.2O.
7. The standard of claim 5, wherein said bulk doping comprises 0.01
to 5% by weight of at least one dopant selected from the group
formed by Cr.sub.2O.sub.3, Ce.sub.2O.sub.3, Eu.sub.2O.sub.3,
Tb.sub.2O.sub.3, Er.sub.2O.sub.3 and Tm.sub.2O.sub.3.
8. The standard of claim 7, wherein said base material is doped
with from 0.05 to 0.3% by weight Er.sub.2O.sub.3 and 0.5 to 2% by
weight of Eu.sub.2O.sub.3.
9. The standard of claim 1, wherein said base material is a
fluorophosphate glass comprising from 5 to 40% by weight of
P.sub.2O.sub.5 and from 60 to 95% by weight of fluoride.
10. The standard of claim 1, wherein said base material is a glass
selected from the group formed by an optical fluorcrown glass and a
lanthanum glass.
11. A standard for referencing luminescence signals, comprising an
optically transparent base material, said base material being
selected from the group formed by a lanthanum phosphate glass and
an optical fluor-crown glass; said base material further comprising
a bulk doping with at least one luminescent component selected from
the group formed by a rare earth and a nonferrous metal; wherein
said base material comprises 0.5 to 2% by weight of
La.sub.2O.sub.3, 10 to 20% by weight of B.sub.2O.sub.3, 5 to 25% by
weight of SiO.sub.2, 10 to 30% by weight of SrO, 2 to 10% by weight
of CaO, 10 to 20% by weight of BaO, 0.5 to 3% by weight of
Li.sub.2O, 1 to 5% by weight of MgO, 20 to 50% by weight of F, and
up to 1 wt.-% of refining agents.
12. The standard of claim 11, wherein said bulk doping comprises
from 3 to 100 ppm of at least one component selected from the group
formed by cobalt, chromium, and manganese.
13. The standard of claim 1, wherein said base material is an
optical glass which comprises 30 to 60% by weight of
La.sub.2O.sub.3, 30 to 50% by weight of B.sub.2O.sub.3, 1 to 5% by
weight of SiO.sub.2, 1 to 15% by weight of ZnO, 2 to 10% by weight
of CaO, and up to 3 wt.-% of refining agents.
14. The standard of claim 10, wherein said bulk doping comprises
from 3 to 100 ppm of at least one component selected from the group
formed by cobalt, chromium, and manganese.
15. The standard of claim 11, wherein said bulk doping comprises
0.01 to 5% by weight of at least one dopant selected from the group
formed by Cr.sub.2O.sub.3, Ce.sub.2O.sub.3, Eu.sub.2O.sub.3,
Tb.sub.2O.sub.3, Er.sub.2O.sub.3 and Tm.sub.2O.sub.3.
16. The standard of claim 11, wherein said base material has a
water content of less than 0.01% by weight and is prepared from raw
materials containing less than 100 ppm of rare earths.
17. The standard of claim 1, wherein said base material consists of
a lithium aluminosilicate glass-ceramic, and wherein said bulk
doping comprises at least one component selected from the group
formed by Eu.sub.2O.sub.3, Er.sub.2O.sub.3, and
Sm.sub.2O.sub.3.
18. The standard of claim 1, wherein said base material has a water
content of less than 0.01% by weight and is prepared from raw
materials containing less than 100 ppm of rare earths.
19. The standard of claim 10, wherein said base material has a
water content of less than 0.01% by weight and is prepared from raw
materials containing less than 100 ppm of rare earths.
20. A standard for referencing luminescence signals, comprising: a
substrate made of a material which is substantially
non-luminescent; a coating made of an optically transparent base
material being selected from the group formed by a glass and a
glass-ceramic, and including a doping with at least one luminescent
component, wherein said coating is a vaporized and subsequently
deposited material comprising said base material and said doping on
said substrate.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to a standard for referencing
luminescence signals and to a process for producing a standard of
this type, and also to advantageous applications of a standard of
this type.
[0002] For the purpose of this disclosure the term luminescence is
understood as to include luminescence, fluorescence or both.
[0003] In addition to the desired measurement data from the
analysis, the results of luminescence measurements also include
device-dependent contributions which make it very difficult or
virtually impossible to compare luminescence measurement data
across device and laboratory boundaries and to achieve long-term
comparability. For luminescence measurement data in the spectral
region ranging from UV to NIR (near infrared) to be comparable, it
is necessary to standardize the spectral parameters and the
sensitivity parameters of luminescence measurement systems.
Furthermore, the wavelength accuracy and the linearity of the
detection systems typically have to be tested. Defined reference
systems, such as for example luminescence standards, are required
to solve this problem. The standardization of the spectral
characteristics of luminescence measurement systems may take place
independently of the standardization of the sensitivity parameters,
which requires either luminescence intensity standards or absolute
measurements of the luminescence intensity or of the luminescence
quantum yield. As an alternative to physical transfer standards,
such as for example receiver standards for determining the
wavelength dependency of the spectral illumination intensity of the
excitation channel of standard lamps or radiance standards for
determining the wavelength dependency of the spectral sensitivity
of the emission channel, it is also possible for chemical transfer
standards, or what are known as luminescence standards, to be used
for the spectral characterization of luminescence measurement
systems. In this context, for the standardization of the spectral
characteristics of luminescence measurement systems it is
sufficient to use spectral luminescence standards with "technical"
luminescence spectra corrected (for device-specific influences),
given as relative or standardized luminescence intensities,
attributable to the primary radiometric standard "black beam"
and/or cryoradiometer.
[0004] In addition to spectral standards and intensity standards,
standards which are simple to handle and have as high a long-term
stability as possible are required for the characterization and
testing of the wavelength accuracy, for the characterization of the
day-to-day performance and for the recording of the device ageing
(spectral effects and sensitivity). The demands which are imposed
on standards for the referencing of luminescence signals (referred
to below as "luminescence standards") include, depending on the
particular application area, inter alia [0005] depending on the
composition, luminescence in the UV to NIR spectral region, [0006]
luminescence spectra which are as unstructured and wide as possible
for spectral standards, [0007] a high and known purity, [0008] the
minimum possible overlap between absorption and emission spectra;
[0009] a wavelength-independent quantum yield of the luminescence
(in the spectral region used for the device characterization),
[0010] an isotropic emission, [0011] a low variation in the
intensity at a statistically relevant number of measurement points,
i.e. a high homogeneity, [0012] a temperature dependency of the
luminescence which is as low as possible and/or known in the
relevant ambient temperature range, [0013] luminescence lives in
the nanosecond, microsecond or millisecond range (for lifetime
standards), [0014] as many narrow bands as possible in the UV to
NIR spectral region (for wavelength standards, day-to-day
per-formance, long-term stability, intensity standards), [0015] a
known and sufficient long-term stability (thermal and
photochemical), [0016] a high reproducibility in the case of
single-use standards, [0017] the possibility of measuring sample
and transfer standard under identical measurement conditions (for
example including identical measurement parameters and measurement
geometry, sample formats, such as cuvette, slide, microtiter
plate), at comparable signal intensities/photon counting rates,
with emission characteristics that are as similar as possible.
[0018] To make luminescence properties, which are generally
measured in arbitrary and relative units, comparable, in the prior
art luminescence standards are known, but in may cases these
standards do not have a sufficient long-term stability, homogeneity
or isotropy, or else they comprise toxic or environmentally harmful
materials, such as for example cadmium or uranium.
[0019] For example, U.S. Pat. No. 4,302,678 discloses a standard
for the calibration of a system which scans in the UV region and is
used for the detection of surface defects on workpieces. The
standard consists of a yellow potassium borosilicate glass which
comprises uranium oxide. The use of uranium oxide is regarded as
disadvantageous on account of the associated safety measures
required and also problems of environmental protection.
Furthermore, a standard of this type does not have the required
photostability and long-term stability.
[0020] U.S. Pat. No. 6,770,220 discloses standards for the
referencing of fluorescence signals which include sol-gel glasses,
other glasses or polymers incorporating luminescent microparticles
or nanoparticles. These are in particular luminescent nanoparticles
of polymers and metal-ligand complexes of ruthenium, osmium,
rhenium, iridium, platinum or palladium.
[0021] U.S. Pat. No. 6,123,872 discloses a luminescent glass with a
long-lasting afterglow which can be used as night illumination or a
night signal or as a material for confirming an infrared laser or
the like. This is an oxide glass which, when excited by radiation
such as gamma rays, X-rays or UV-rays, can have a long-lasting
afterglow and photostimulated luminescence, the glass comprising
from 1 to 55% by weight of SiO.sub.2, from 1 to 50% by weight of
B.sub.2O.sub.3, from 30 to 75% by weight of ZnO, further optional
constituents and terbium or manganese as fluorescent agent.
[0022] However, a glass of this type cannot be used as a
luminescence standard.
[0023] A range of colored glasses which can be used as steep edge
filters are known as filter glasses. These include U.S. Pat. No.
6,667,259 which discloses an optical colored glass for a steep edge
filter which may comprise from 30 to 75% by weight of SiO.sub.2, 5
to 35% by weight of K.sub.2O, to 5% by weight of TiO.sub.2, 4 to 7%
by weight of B.sub.2O.sub.3, 5 to 30% by weight of ZnO, 0.01 to 10%
by weight of F and 0.1 to 3% by weight of copper, silver, indium,
gallium, aluminium, yttrium, sulphur, selenium or tellurium. This
is a colored flash glass in which the coloration is produced by
colloidal precipitation of semiconductor compounds during cooling
of the melt or by subsequent heat treatment.
[0024] Further colored glasses of a similar type are known from
U.S. patent application US 2005/0054515 A1 and from U.S. Pat. No.
4,106,946.
[0025] U.S. Pat. No. 3,773,530 discloses a further colored glass
for a filter, which comprises cadmium sulphide as coloring
constituent.
[0026] The photostability of colored glasses of this type is not
sufficient to allow them to be used as luminescence standards.
[0027] Luminescence standards with fluorescent polymer layers on a
non-fluorescent support are known from WO 02/077620 A1.
[0028] WO 01/59503 A2 discloses a luminescence standard having a
substrate, for example made from quartz, to which a patterned
surface of fluorescent material is applied.
[0029] DE 202004002064 U1 discloses a microarray support, which
includes a substantially non-fluorescent substrate as support and
at least one standard for fluorescence measurements which includes
a colored glass. The colored glass comprises semiconductor
compounds, which may be cadmium-semiconductor compounds or copper-,
silver, indium-, gallium-, aluminium-, sulphur- or
selenium-semiconductor compounds. The colored glasses comprise 30
to 75% by weight of SiO.sub.2, 5 to 35% by weight of K.sub.2O, 0 to
5% by weight of TiO.sub.2, 0.01 to 10% by weight of fluorine and
0.01 to 3% by weight of M'M'''Y''.sub.2, where M' is Cu.sup.+
and/or Ag.sup.+, M''' is In.sup.3+ and/or Ga.sup.3+ and/or
Al.sup.3+ and Y'' is S.sup.2- and/or Se.sup.2-. The fluorescent
semiconductor compounds are in the form of colloidal nanocrystals
distributed through the glass.
[0030] Furthermore, however, there is a need for standards which
are distinguished by a particularly high quality, i.e. in
particular have a high homogeneity and isotropy, a low temperature
dependency and a good long-term stability and photostability.
Standards of this type could also satisfy further requirements,
such as for example checking of the spectral sensitivity and
wavelength accuracy. The time axis in time-resolved luminescence
measurements could also be checked.
[0031] The colored glasses which are known in the prior art have
proven not to satisfy these requirements, since they are not
photostable. The other luminescence standards which are known in
the prior art are also not of sufficient quality.
SUMMARY OF THE INVENTION
[0032] It is a first object of the invention to disclose a standard
for referencing luminescence signals (a luminescence standard)
which as far as possible avoids the drawbacks of the prior art and
is of as high a quality as possible.
[0033] It is a second object of the invention to disclose a method
for producing a standard of this type and an advantageous
application for a standard of this type.
[0034] It is a third object of the invention to disclose a
luminescence standard which can be used in the UV to NIR spectral
range.
[0035] It is a forth object of the invention to disclose a
luminescence standard which is of a high and known purity.
[0036] It is a fifth object of the invention to disclose a
luminescence standard having a minimum possible overlap between
absorption and emission spectra.
[0037] It is a sixth object of the invention to disclose a
luminescence standard having a wavelength-independent quantum yield
of the luminescence (in the spectral region used for the device
characterization).
[0038] It is a seventh object of the invention to disclose a
luminescence standard having an isotropic emission and a low
variation in the intensity at a statistically relevant number of
measurement points, i.e. a high homogeneity.
[0039] It is an eighth object of the invention to disclose a
luminescence standard having a temperature dependency of the
luminescence which is as low as possible and/or known in the
relevant ambient temperature range.
[0040] It is a ninth object of the invention to disclose a
luminescence standard having a luminescence live in the nanosecond,
microsecond or millisecond range.
[0041] It is a tenth object of the invention to disclose a
luminescence standard having as many narrow bands as possible in
the UV to NIR spectral region.
[0042] It is a further object of the invention to disclose a
luminescence standard having a known and sufficient long-term
stability (thermal and photochemical).
[0043] It is a further object of the invention to disclose a
luminescence standard having a high reproducibility (single-use
standard).
[0044] It is a further object of the invention to disclose a
luminescence standard providing the possibility of measuring sample
and transfer standard under identical measurement conditions (for
example including identical measurement parameters and measurement
geometry, sample formats, such as cuvette, slide, microtiter
plate), at comparable signal intensities/photon counting rates,
with emission characteristics that are as similar as possible.
[0045] These and other objects of the invention are achieved by a
standard for referencing luminescence signals, having an optically
transparent base material comprising a lanthanum phosphate glass, a
fluorophosphate glass, a fluorcrown glass, a lanthanum glass, a
glass-ceramic formed therefrom or a lithium aluminosilicate
glass-ceramic, the base material comprising a bulk doping with a
rare earth and/or a nonferrous metal, in particular cobalt,
chromium or manganese, which is fluorescent or luminescent.
[0046] In this way, the object of the invention is entirely
achieved.
[0047] A luminescence standard according to the invention is
distinguished by a particularly good homogeneity, isotropy,
long-term stability and photostability.
[0048] On account of its high quality, the luminescence standard
according to the invention can be used for a very wide range of
applications. By way of example it can be used as a luminescence
standard for characterizing the long-term stability of luminescence
measurement systems. It can also be used as a wavelength standard,
as a luminescence intensity and luminescence lifetime standard for
the spectral region from UV to NIR and for comparability and
standardization of luminescence measurement data. In this context,
statements can be made as to any change in the spectral sensitivity
of the detection system and of the wavelength accuracy, as to the
determination and characterization of the wavelength accuracy, as
to the calibration of luminescence intensities and as to the
characterization and calibration of luminescence measurement
systems with time-resolved luminescence detection in the UV to NIR
spectral region. Furthermore, the standard according to the
invention is suitable as a reference system or standard for
characterization of the (intrinsic) luminescence of materials in
the UV to NIR spectral region from 250 to 1700 nm.
[0049] The lifetime/decay times can be "set" by stipulating the
base material, by the concentration of the doping and by Redox
processes.
[0050] The absorption and emission effect cross sections can be
varied within wide limits, in particular if a glass-ceramic is used
as base material.
[0051] Unlike with colored glasses known in the prior art, the
crystallites in the glass-ceramic according to the invention (for
example doped Robax.RTM.) are>10 nm. In the standard according
to the invention, the luminescent dopant is not incorporated
colloidally, as in the case of standards known in the prior
art.
[0052] If dopants including nonferrous metals are used, wide,
unstructured emission bands result, and the standards can be
applied all the way into the NIR region (for example in the case of
dopings with Cr.sup.3+). The prior art has not hitherto disclosed a
spectral fluorescence standard for the NIR region.
[0053] If dopants comprising rare earths are used, sharp line
spectra result, which can be used, for example, for wavelength
calibration and/or for checking the wavelength accuracy and for
determining the spectral resolution of luminescence measurement
systems.
[0054] The luminescence standards according to the invention can be
produced for various measurement geometries and formats, i.e. for
example in cuvette form, in slide form as microplates and in other
forms.
[0055] The fluorescence intensity can be influenced in a suitable
way by varying the dopant concentration.
[0056] According to a further configuration of the invention, the
base material is a lanthanum phosphate glass which comprises 30 to
90% by weight of P.sub.2O.sub.5, preferably 50 to 80% by weight,
particularly preferably 60 to 75% by weight of P.sub.2O.sub.5, as
well as standard quantities of refining agents.
[0057] Furthermore, the lanthanum phosphate glass may comprise 1 to
30% by weight of La.sub.2O.sub.3, preferably 5 to 20% by weight,
particularly preferably 8 to 17% by weight of La.sub.2O.sub.3.
[0058] Furthermore, the base material preferably comprises 1 to 20%
by weight of Al.sub.2O.sub.3, preferably 5 to 15% by weight of
Al.sub.2O.sub.3, and 1 to 20% by weight of R.sub.2O (alkali metal
oxide), which may preferably be 1 to 20% by weight of K.sub.2O,
preferably 5 to 15% by weight of K.sub.2O.
[0059] According to a further configuration of the invention, the
base material is doped with Cr.sub.2O.sub.3, preferably with 0.01
to 5% by weight, particularly preferably with 0.02 to 2% by weight
of Cr.sub.2O.sub.3.
[0060] According to a further configuration of the invention, the
base material is doped with Ce.sub.2O.sub.3, Eu.sub.2O.sub.3,
Tb.sub.2O.sub.3 and/or Tm.sub.2O.sub.3.
[0061] If the base material is a fluorophosphate glass, this
material preferably comprises from 5 to 40% by weight of
P.sub.2O.sub.5 and a fluoride content of from 60 to 95% by
weight.
[0062] A base material of this type is preferably doped with 0.01
to 5% by weight, preferably with 0.05 to 2% by weight, of
Er.sub.2O.sub.3 and/or Eu.sub.2O.sub.3.
[0063] By way of example, the base material may in this case be
doped with from 0.05 to 0.3% by weight of Er.sub.2O.sub.3 and 0.5
to 2% by weight of Eu.sub.2O.sub.3, preferably with approximately
0.1% by weight of Er.sub.2O.sub.3 and approximately 1% by weight of
Eu.sub.2O.sub.3.
[0064] Furthermore, according to the invention the base material
may be optical fluor-crown glasses, in particular FK-52 or FK51
(Schott trade names), or a lanthanum glass, in particular LAK-8
(Schott trade name).
[0065] In this case, the base material may, for example, be an
optical glass which comprises 0.5 to 2% by weight of
La.sub.2O.sub.3, 10 to 20% by weight of B.sub.2O.sub.3, 5 to 25% by
weight of SiO.sub.2, 10 to 30% by weight of SrO, 2 to 10% by weight
of CaO, 10 to 20% by weight of BaO, 0.5 to 3% by weight of
Li.sub.2O, 1 to 5% by weight of MgO, 20 to 50% by weight of F, as
well as standard quantities of refining agents.
[0066] If the base material is in the form of lanthanum glass, it
may, for example, comprise 30 to 60% by weight of La.sub.2O.sub.3,
30 to 50% by weight of B.sub.2O.sub.3, 1 to 5% by weight of
SiO.sub.2, 1 to 15% by weight of ZnO, 2 to 10% by weight of CaO and
standard quantities of refining agents.
[0067] Fluor-crown glasses or lanthanum glasses of this type are
preferably doped with from 3 to 100 ppm of non-ferrous metals,
preferably of cobalt, chromium and/or manganese.
[0068] Furthermore, the base material used may be a glass-ceramic,
in particular a lithium aluminosilicate glass-ceramic, such as for
example the transparent glass-ceramics Robax.RTM. (Schott-Internal
designation 87213) or Cleartrans.RTM. (Schott-Internal designation
87233). For this purpose, it is preferable to use a dopant which
comprises Eu.sub.2O.sub.3, Er.sub.2O.sub.3 and/or
Sm.sub.2O.sub.3.
[0069] In this case, it is particularly preferred that the dopant
comprises 0.1 to 5% by weight of Eu.sub.2O.sub.3, 0.01 to 0.5% by
weight of Er.sub.2O.sub.3 and/or 0.1 to 2% by weight of
Sm.sub.2O.sub.3.
[0070] In a preferred refinement of the invention, the base
material is produced from raw materials which comprise at most 100
ppm of rare earths.
[0071] Furthermore, the base material preferably has a water
content of less than 0.1% by weight, preferably of less than 0.01%
by weight.
[0072] This allows quenching and extinction effects to be ruled
out.
[0073] According to a further development of the invention, the
standard according to the invention can be designed as a
self-supporting body, i.e. in particular in cuvette format
(preferably 12.times.12.times.50 mm or smaller), in the microtiter
plate format and specimen slide format (preferably
75.times.25.times.1 mm or smaller) or as a capillary.
[0074] In addition, it is fundamentally also possible, for special
applications, to produce a standard according to the invention
having a substrate formed from a material which is substantially
non-luminescent, to which the base material comprising the dopant
is applied.
[0075] In this case, the base material with the dopant can be
formed as a continuous coating on the substrate.
[0076] On the other hand, it is also possible to apply the base
material with the dopant to the substrate as a patterned
coating.
[0077] Standards of this type, having a substrate comprising a
material which is non-luminescent and with a coating of an
optically transparent base material of glass or glass-ceramic which
includes a dopant with at least one constituent that is
luminescent, can be produced by vaporizing the base material
together with the dopant and by depositing both together on the
substrate.
[0078] In this case, the base material with the dopant can be used
as a target which is locally vaporized by means of an electron beam
and deposited on the substrate.
[0079] If it is desired to form a patterned coating, the substrate
can be provided, prior to the deposition operation, with a masking
which is at least partially removed again after the coating
operation, as is fundamentally known from CA 2479823 A1 (WO
03/088340 A2) which is fully incorporated by reference.
[0080] In this case, the vaporization and deposition may be plasma
ion assisted.
[0081] The process for vaporizing and depositing the doped base
material on a substrate surface is not restricted to the materials
mentioned above, but rather can in principle also be carried out
for other standards consisting of any suitable materials.
[0082] It will be understood that the features of the invention
mentioned above and those which are yet to be explained below can
be used not only in the combination described in each instance, but
also in other combinations or as stand-alone features without
departing from the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0083] Further features and advantages of the invention will emerge
from the following description of preferred exemplary embodiments
with reference to the drawings, in which:
[0084] FIG. 1 shows the results of an irradiation test carried out
on a glass according to the invention compared to a conventional
colored glass, in which the intensity is plotted against the
irradiation time;
[0085] FIG. 2 shows the emission spectra of a lanthanum phosphate
glass according to the invention which is doped with a plurality of
rare earths, compared to a conventional Uranyl glass and
conventional T-phernylbutadiene in PMMA, in each case without
irradiation, after irradiation with UV for 30 minutes and after
irradiation with UV for 60 minutes, with the intensity in arbitrary
units plotted against the wavelength in nanometers;
[0086] FIG. 3 shows the result of measurements for the detection of
the good homogeneity and anisotropy carried out on a
fluorophosphate glass according to the invention which is doped
with 1% of erbium oxide, with the intensity plotted against the
wavelength;
[0087] FIG. 4 shows a diagram corresponding to FIG. 3 of a
fluorophosphate glass which is doped with 1% by weight of
Eu.sub.2O.sub.3, with the intensity again plotted against the
wavelength;
[0088] FIG. 5 shows an illustration corresponding to FIG. 3 for
demonstrating the good anisotropy and homogeneity properties of a
lanthanum phosphate glass which is doped with Eu.sub.2O.sub.3,
and
[0089] FIG. 6 shows the results of measurements for testing the
anisotropy of the glass shown in FIG. 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
EXAMPLE 1
[0090] The compositions of various lanthanum phosphate glasses
which are individually doped with Cr.sub.2O.sub.3 or are multiply
doped with rare earth ions, are summarized in Table 1.
TABLE-US-00001 TABLE 1 OXIDE % by % by % by % by % by weight weight
weight weight weight Specimen A B C D E Al.sub.2O.sub.3 8.498 8.774
8.857 8.498 8.498 P.sub.2O.sub.5 68.378 70.593 71.267 68.378 68.378
K.sub.2O 9.316 6.328 6.388 9.316 9.316 La.sub.2O.sub.3 13.808
14.256 10.669 13.808 13.808 Ce.sub.2O.sub.3 0.126 0.13 1.21
Eu.sub.2O.sub.3 1.24 1.23 Tb.sub.2O.sub.3 2.693 2.63 2.62
Cr.sub.2O.sub.3 0.050 Tm.sub.2O.sub.3 1.02
EXAMPLE 2
[0091] Fluorophosphate glasses which have a P.sub.2O.sub.5 content
of 5 to 40% by weight and a fluoride content of 60 to 96% by weight
are used. Individual dopings of approximately 0.1% by weight of
Er.sub.2O.sub.3 and approximately 1% by weight of Eu.sub.2O.sub.3
are used.
EXAMPLE 3
[0092] Optical fluor-crown glasses FK-52, FK-53 and lanthanum glass
LAK-8 are doped with nonferrous metals, specifically in the range
between 3 and 100 ppm with cobalt, chromium and/or manganese.
[0093] The result is a wide-band emission (420<.lamda.<850
nm) in the excitation range from 400 to 750 nm which is of
relevance to bioanalysis. The compositions of the fluor-crown
glasses FK51 and FK52 and of the lanthanum glass LAK-8 are given in
Table 2. TABLE-US-00002 TABLE 2 Oxide % by weight % by weight Glass
FK51/FK52 LAK-8 La.sub.2O.sub.3 0.5-2% 30-60% B.sub.2O.sub.3 10-20%
30-50% SiO.sub.2 5-25% 1-5% SrO 10-30% CaO 2-10% 2-10% BaO 10-20%
Li.sub.2O 0.5-3% MgO 1-5% F 20-50% ZnO 1-15%
EXAMPLE 4
[0094] A lithium-aluminium glass-ceramic (LAS glass-ceramic) is
doped with rare earths. In particular the LAS glass-ceramic
marketed by Schott under the trademark Ceran.RTM. can be used for
this purpose. In this case, by way of example, approximately 0.1 to
5% by weight of Eu.sub.2O.sub.3, 0.01 to 0.5% by weight of
Er.sub.2O.sub.3 and/or 0.1 to 2% by weight of Sm.sub.2O.sub.3 can
be added.
[0095] The results of various tests aimed at demonstrating the
photostability, homogeneity and anisotropy of various glasses
according to the invention are explained in more detail below with
reference to FIGS. 1 to 6.
[0096] FIG. 1 shows the demonstration of the photostability carried
out on glass C from Table 1 compared to the conventional colored
glass OG2 (52% by weight of SiO.sub.2, 22.5% by weight of K.sub.2O,
3.9% by weight of B.sub.2O.sub.3, 19.5% by weight of ZnO, 1.2% by
weight of CdS, 0.63% by weight of Na.sub.2SeO.sub.3 and 0.1% by
weight of Cd).
[0097] Irradiation was carried out using a Xenon lamp in the
spectral regions 450 to 490 and 510 to 555 nm.
[0098] Whereas the lanthanum phosphate glass according to the
invention with rare earths doping has an intensity drop of less
than 5% even after an irradiation time of 4 minutes, the
conventional colored glass OG2 has a considerable drop in intensity
even after a short time.
[0099] FIG. 2 shows the results of irradiation with a 10W lamp
HOK-4, which emits at 365 nm, with subsequent excitation at 365 nm.
The multiply rare earth doped lanthanum phosphate glass C (Table 1)
and a Uranyl Glass GG17 and a T-phernylbutadiene in PMMA are shown
for comparison purposes. The intensity measured is plotted in
arbitrary units against the wavelength.
[0100] It can be seen from the illustration that the polymeric
fluorescent material comprising T-phernylbutadiene in PMMA reveals
a considerable drop in intensity after irradiation (cf. maximum at
425 nm). The Uranyl glass GG17, the maximum of which is approx. 540
nm, also has a noticeable drop in intensity after irradiation, i.e.
is not photostable.
[0101] The standard according to the invention (specimen C
according to Table 1) reveals a series of pronounced intensity
maxima at approx. 415, 435, 480, 550, 580 and approximately 620 nm.
Scarcely any intensity differences are discernible between the
unirradiated state and the state after 30 or 60 minutes of
irradiation.
[0102] FIG. 3 shows the result of the anisotropy and homogeneity
test carried out on a fluorophosphate glass with an individual
doping of approximately 1% by weight of Er.sup.3+. The glass
composition was as follows (in mol. %) : 35% AlF.sub.3, 15%
SrF.sub.2, 30% CaF.sub.2, 10% MgF.sub.2, 20% P.sub.2O.sub.5.
[0103] The excitation took place at 378 nm, and measurement was
carried out at 0.degree. (reflection) and 90.degree.. The
measurement was background- and spectrum-corrected. The homogeneity
was tested on the basis of four measurement points (N=4). The
plotting of the intensity (in arbitrary units) against the
wavelength uses the error bars to demonstrate that overall the
anisotropy is very low (0.02732) and the homogeneity is very good.
The illustration additionally indicates the measured wavelength
maxima at 522, 540 and 551 nm.
[0104] FIG. 4 shows a corresponding testing of the homogeneity and
anisotropy of a fluorophosphate glass which is doped with 1% by
weight of Eu.sup.3+. The excitation was carried out at 404 nm.
Measurement was carried out at 0.degree. and 90.degree.
(reflection). The measurement was background- and
spectrum-corrected. The anisotropy was determined as 0.01407. The
homogeneity was tested at four measurement points.
[0105] Once again, a very good anisotropy and homogeneity were
found.
[0106] FIG. 5 shows a corresponding testing of a lanthanum
phosphate glass corresponding to specimen C (cf. Table 1). The
excitation took place at 365 nm. Measurement was carried out at
0.degree. and 90.degree. (reflection). The measurement was
background- and spectrum-corrected. The anisotropy was determined
as 0.00783. The homogeneity was tested at four measurement
points.
[0107] In this case too, a very low anisotropy and a very good
homogeneity were found.
[0108] Finally, FIG. 6 shows the measurement of the anisotropy on
the lanthanum phosphate glass specimen C (cf. Table 1) as a
function of the excitation/emission direction. In this case, the
measurements were carried out as follows: Measurements took place
at 0.degree. (normal situation) and 90.degree.. The emission was
measured at 0.degree. (measurement point 1) or 90.degree.
(measurement point 3) and at 0.degree. (measurement point 2) or
180.degree. (measurement point 4), respectively. In addition,
measurements were carried out at various height positions of the
specimen (measurement points 5 and 7, and 6 and 8, respectively).
Measurement points 9 and 10 represent the anisotropy measurements
for the 0-180.degree. arrangement, i.e. in transmission. The
anisotropy values are then given (in arbitrary units) relative to
the conventional 0-90.degree. arrangement
(excitation/emission).
[0109] This again demonstrates a very good isotropy of the material
tested.
[0110] The standards according to the invention can be produced
substantially by processes which are known to the person skilled in
the art, in which particularly pure starting materials (less than
100 ppm of rare earths) are used and the glasses are melted "dry",
so that the water content is preferably less than 0.01% by
weight.
[0111] The luminescent or fluorescent constituents (fluorophores)
used can be supplied to the base material in the form of oxides or
fluorides during the melting of the glass.
[0112] The known production processes begin with the melting of the
glass composition (comprising the steps of melting down the batch,
refining, homogenizing and conditioning). The melting-down takes
place in ceramic crucibles at temperatures from approximately 1100
to approximately 1550.degree. C., preferably in the range from
approximately 1200 to 1360.degree. C. The melting until seed-free
(refining) is preferably carried out at a slightly lower
temperature, for example at approximately 1200 to 1400.degree. C.
After a standing phase, the temperature is lowered in the usual way
in order to homogenize the melt. Casting typically takes place into
a suitable mould at between approximately 950 and 1050.degree.
C.
[0113] If a lithium-aluminosilicate (LAS) glass-ceramic is used, a
heat treatment which is known for glass-ceramics of this type is
carried out for nucleation and subsequent ceramization.
[0114] If the quality demands are particularly high, the melting
can be carried out in platinum crucibles or ceramic crucibles lined
with platinum, in order to secure a particularly high purity.
[0115] If a base material which has been volume-doped in accordance
with the invention is to be deposited as a coating on a support
which is substantially non-luminescent, evaporation and subsequent
deposition can be carried out, as is fundamentally known from
Canadian patent application CA 2479823 A1 (WO 03/088340 A2) and
from Canadian patent application CA 2480691 (WO 03/087424 A1) which
are fully incorporated by reference herewith.
[0116] To do this, it is possible to use an electron beam generator
with a radiation deflection device and a glass target onto which an
electron beam is directed. At the location where the electron beam
impinges on the target, the glass is vaporized and is then
precipitated on the substrate that is to be coated. To enable the
glass of the target to be vaporized as uniformly as possible, the
target is rotated and the electron beam executes a scanning motion.
In addition the arrangement may also comprise a plasma source for
the generation of an ion beam which, in operation, is directed onto
the side that is to be coated in order for the substrate to be
coated with the doped glass layer by means of plasma ion assisted
deposition (PIAD).
[0117] If it is desired to produce a patterned luminescence
standard on a substrate, the substrate is first of all provided
with a masking by means of a standard masking process, with the
masking being at least partially removed again following the
coating operation.
* * * * *