JP2013024570A - Phosphorescence measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple phosphorescence measuring method which allows troublesome separation of fluorescence and phosphorescence to be accurately performed based on a conventional measurement method at low temperature without new modification of a device.SOLUTION: A phosphorescence measuring method comprises the steps of: sequentially irradiating an object to be measured with two excitation lights having different output intensity, sequentially detecting two kinds of data (emission intensity versus wavelength) for the light emitted from the object to be measured, calculating two kinds of normalized data through normalization processing on the basis of the maximum emission intensity of the respective data, and detecting the phosphorescence spectrum of the object to be measured by obtaining the absolute value of difference between the two kinds of normalized data.

Description

  The present invention relates to a method for measuring phosphorescence of an object to be measured.

  Substances are excited by receiving energy by electromagnetic waves, heat, friction, etc., and have the property of emitting the received energy as light of a specific wavelength, so-called luminescence. It is very important to investigate the optical properties of materials in order to find effective uses of materials.

  Usually, by irradiating a substance with excitation light, light emission such as fluorescence derived from the substance, phosphorescence, etc. can be obtained. In the case of fluorescence, the emission lifetime is several nanoseconds to several hundred nanoseconds, In some cases, it is micro-millisecond (longer in some cases), and phosphorescence is characterized by a very long lifetime compared to fluorescence.

  Therefore, when only phosphorescence is to be measured out of these emissions, phosphorescence is measured using a time-resolved measurement method, but in addition, extremely low temperatures (specifically, 10K) at which phosphorescence is easily detected. == 263 ° C.) Measurement (low temperature measurement method) is performed. However, in the time-resolved measurement method, there is a problem that phosphorescence intensity sufficient for measurement cannot be obtained, and in the low-temperature measurement method, it is difficult to separate from fluorescence detected at the same time. Furthermore, a measurement method combining a time-resolved method and a low-temperature measurement has been studied, but has many problems in adjusting the measurement environment.

  In addition, the measurement environment and the measurement system can be improved to improve the accuracy of fluorescence and phosphorescence measurements, and the detection results can be processed by incorporating multiple circuits into the measurement device. And a method for measuring fluorescence simultaneously and accurately have been proposed. (For example, refer to Patent Documents 1 and 2).

JP-A-8-136458 JP 2002-71566 A

  On the other hand, in one embodiment of the present invention, no new apparatus is improved, and the conventional low-temperature measurement method is used as a basis, and the problem of fluorescence and phosphorescence is accurately separated, and phosphorescence measurement is performed. A method for simply carrying out the above is provided.

  In one embodiment of the present invention, two types of excitation light having different output intensities are sequentially irradiated onto a measurement object, and two types of data (emission intensity with respect to wavelength) based on light emitted from the measurement object are sequentially By detecting and standardizing each of these data based on the maximum emission intensity of each data, two types of standardized data are calculated, and the absolute value of the difference between the two types of standardized data is obtained. A phosphorescence measuring method characterized by detecting a phosphorescence spectrum of a measurement object.

  In one embodiment of the present invention, two types of excitation light with different output intensities are sequentially irradiated onto the object to be measured, and two types of data based on the light emitted from the object to be measured (for example, emission intensity with respect to the wavelength of light). Two types of normalized data obtained by a normalization process based on the maximum emission intensity in each of the two types of data are calculated sequentially, and the phosphorescence spectrum of the object to be measured is calculated from the absolute value of the difference between the two types of normalized data. Is a method for measuring phosphorescence.

  In another configuration of the present invention, the object to be measured is irradiated with the first excitation light, and the first data (for example, emission intensity with respect to the wavelength of the light) based on the light emitted from the object to be measured is detected. Irradiating the object to be measured with second excitation light having an output intensity different from that of the first excitation light, and obtaining second data (for example, emission intensity with respect to the wavelength of the light) based on the light emitted from the object to be measured. First normalization data detected and obtained by normalization processing based on the maximum light emission intensity in the first data, and second normalization data obtained by normalization processing based on the maximum light emission intensity in the second data, A phosphorescence measurement method characterized in that a phosphorescence spectrum of an object to be measured is obtained from the absolute value of the difference between the two.

  According to one embodiment of the present invention, a method for performing phosphorescence measurement simply by accurately separating fluorescent light and phosphorescence, which is based on the conventional low-temperature measurement method, without improving a new apparatus or the like. Can be realized.

4A and 4B illustrate a phosphorescence measurement method which is one embodiment of the present invention. 4A and 4B illustrate a phosphorescence measurement method which is one embodiment of the present invention. FIG. 6 shows an emission spectrum of NPB (abbreviation) which is one embodiment of the present invention. FIG. 10 shows light emission intensity with respect to output intensity of excitation light of NPB (abbreviation) which is one embodiment of the present invention. FIG. 9 shows normalized data of NPB (abbreviation) which is one embodiment of the present invention. FIG. 13 shows a phosphorescence spectrum of NPB (abbreviation) which is one embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and various changes can be made in form and details without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments below. Moreover, even if it is different drawing, what attached | subjected the same code | symbol shall show the same thing, and abbreviate | omits description.

(Embodiment 1)
In this embodiment, a phosphorescence measurement method which is one embodiment of the present invention will be described.

  A specific structure of the phosphorescence measurement method which is one embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1, first, a first excitation light (Ex) having a predetermined output intensity is irradiated on the object to be measured. Then, the first data based on the light (PL) emitted from the object to be measured is detected by the detector by being irradiated with the first excitation light.

  The first data detected here is spectral data based on the fluorescence emission and phosphorescence emission of the object to be measured.

  Next, the object to be measured is irradiated with second excitation light (Ex ′) having an output intensity different from that of the first excitation light. Then, when the second excitation light is irradiated, second data based on the light (PL ′) emitted from the object to be measured is detected by the detector. The second data is also spectral data based on the fluorescence emission and phosphorescence emission of the object to be measured.

  Next, normalization processing is performed on the first data with reference to the maximum emission intensity of the fluorescence emission in the first data, thereby calculating the first normalized data, and the second data On the other hand, the second normalized data is calculated by performing a standardization process based on the maximum emission intensity of the fluorescence emission in the second data.

  Finally, the phosphorescence spectrum of the object to be measured can be detected with high accuracy by performing an arithmetic process that takes the absolute value of the difference between the first normalized data and the second normalized data.

  In this embodiment, a fluorescent phosphorescence measurement apparatus 200 manufactured by LabRAM HR-PL: Horiba, Ltd. is used to perform phosphorescence measurement. A simple structure of the fluorescent phosphorescence measuring apparatus 200 is as shown in FIG. 2A, and the measurement is performed at a low temperature (10K = −263 ° C. or lower). Since measurement at a low temperature (10K = −263 ° C. or lower) can prevent thermal deactivation of energy from the triplet excitation energy level (T1 level) of the object to be measured during measurement, light emission Measurements with as little spectral intensity loss as possible are possible.

  2A includes a light source 201 that outputs excitation light, a holder 203 for providing a measurement sample 202, a beam splitter 204 and an objective lens 205 that control an optical path, and also emits from the measurement sample. A spectroscope 206 for splitting the light to be split, and a detector 207 for detecting the split light.

  The excitation light output from the light source 201 can be output in the range of 1 nW or more and 15 mW or less, and excitation light having different output intensities can be sequentially irradiated onto the measurement sample. In the present embodiment, a He—Cd laser [325 nm] (manufactured by Kinmon Konami Co., Ltd.) is used for the output of excitation light.

  An example of a measurement sample provided with the object to be measured is shown in FIG. A thin film of an object to be measured 212 is provided between a pair of substrates (210, 211) and sealed with a sealant 213. In addition, as a material of a board | substrate (210, 211), what has translucency is preferable, for example, FRP (Fiberglass-Reinforced Plastics), PVF (polyvinyl fluoride), polyester, an acrylic other than a glass substrate or a quartz substrate A plastic substrate made of, for example, can be used, and a quartz substrate is particularly preferable. The space 214 in which the thin film of the object to be measured 212 is disposed is preferably an inert gas (nitrogen, argon, or the like) atmosphere. In addition, as the object to be measured 212, an organic compound exhibiting fluorescence and phosphorescence is used. Further, it is preferable to use an epoxy resin for the sealant 213. Moreover, it is desirable that these materials are materials that do not transmit moisture and oxygen as much as possible.

  Here, as an object to be measured, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (abbreviation: NPB or an organic compound known as an EL material used for an organic EL element) Specific phosphorescence measurement in the case of using (α-NPD) will be described.

  In a measurement sample provided with NPB (abbreviation), a thin film of NPB (abbreviation) is formed with a film thickness of 50 nm on one quartz substrate by vapor deposition, and then one quartz substrate and the other quartz substrate are sealed together. It is formed by pasting together. That is, a thin film of NPB (abbreviation) is disposed in a space 214 surrounded by a pair of substrates and a sealing material. Note that the space 214 is filled with nitrogen.

  In order to measure an object to be measured using the produced measurement sample, the measurement sample 202 having NPB (abbreviation) is provided in the holder 203 of the fluorescent phosphorescence measurement apparatus 200 shown in FIG. The measurement sample 202 is irradiated with laser light (Ex = 4 μW) as the first excitation light. A beam splitter 204 and an objective lens 205 are arranged on the optical path of the first excitation light.

  The light (PL) emitted from the measurement sample 202 by being irradiated with the first excitation light is dispersed by the spectroscope 206 and then detected as first data by the detector 207. Similarly, laser light (Ex ′ = 400 μW) is irradiated from the light source 201 to the measurement sample 202 as second excitation light having a different output intensity from the first excitation light. The light (PL ′) emitted from the measurement sample 202 by being irradiated with the second excitation light is detected as second data by the detector 207.

  First data detected by the detector 207 by outputting the first excitation light (Ex = 4 μW) and detected by the detector 207 by outputting the second excitation light (Ex ′ = 400 μW) The second data are shown in FIG. In FIG. 3, the horizontal axis indicates the wavelength (nm), and the vertical axis indicates the emission intensity (arbitrary unit).

  From the results of FIG. 3, in both the first data and the second data, fluorescence showing an emission peak around 450 nm is seen, but the phosphorescence emission peak that should be seen around 550 nm is the fluorescence emission peak. It can be seen that it is difficult to confirm whether they overlap.

  Here, FIG. 4 shows the result of measurement using NPB (abbreviation) as the object to be measured, regarding the difference between the emission intensity of fluorescence and phosphorescence emitted from the object to be measured in accordance with the output intensity of the excitation light. In FIG. 4, the horizontal axis indicates the output intensity (W) of the excitation light, and the vertical axis indicates the emission intensity (arbitrary unit) with respect to the output intensity (W) of the excitation light. From the result of FIG. 4, the output intensity of the excitation light increases, but the emission intensity in the fluorescence also increases (it tends to be linear), so the emission efficiency does not change much, but the output intensity of the excitation light with respect to phosphorescence. In contrast, the emission intensity in phosphorescence becomes weak (it tends to be saturated), so that the light emission efficiency decreases. This tendency seen in phosphorescence emission is already known in other materials and is said to be due to concentration quenching.

  Therefore, in the phosphorescence measurement method which is one embodiment of the present invention, this phenomenon is used, and a region in which the emission efficiency of phosphorescence emission is not significantly reduced with respect to the object to be measured (the emission intensity with respect to the excitation light output intensity tends to be linear). The first excitation light having the output intensity of the region is different from the first excitation light, and the emission efficiency of phosphorescence emission to the object to be measured decreases (the emission intensity with respect to the excitation light output intensity tends to be saturated). (A certain region) (indicated by 400 in FIG. 4), that is, the second excitation light that is the excitation light of the output intensity included in the region where concentration quenching occurs, and sequentially obtained two types of spectral data, The phosphorescence spectrum of the object to be measured is detected by performing normalization processing based on the respective maximum emission intensities and taking the absolute value of the difference between the obtained two types of normalized spectrum data.

  That is, in the present embodiment, the output intensity in the region where the emission efficiency in the phosphorescence of the object to be measured does not change much (the region where the emission intensity with respect to the excitation light output intensity tends to be linear) is set to the output intensity of the first excitation light (Ex = 4 μW), and the output intensity in the region where the emission efficiency in phosphorescence of the object to be measured is reduced (the region where the emission intensity with respect to the excitation light output intensity tends to be saturated) (indicated by 400 in FIG. 4) is the second excitation. In this example, the light output intensity (Ex ′ = 400 μW) is set, and two types of excitation light having different output intensities are sequentially irradiated to detect two types of spectrum data.

  After detecting the two types of spectrum data, the first data obtained by outputting the first excitation light (Ex = 4 μW) is normalized by the maximum emission intensity (fluorescence emission) in the first data, and the first data 1 standardized data is obtained. Similarly, the second data obtained by outputting the second excitation light (Ex ′ = 400 μW) is normalized by the maximum emission intensity (fluorescence emission) in the second data to obtain second normalized data. . The first normalized data and the second normalized data obtained by normalization are as shown in FIG. In FIG. 5, the horizontal axis represents wavelength (nm) and the vertical axis represents emission intensity (arbitrary unit).

  From the result of FIG. 5, the emission peak of phosphorescence near 550 nm can be confirmed in the first normalized data obtained by the output of the first excitation light (Ex = 4 μW). That is, the phosphorescence emission intensity with respect to the fluorescence emission intensity in the first data and the phosphorescence emission intensity with respect to the fluorescence emission intensity in the second data are emitted according to the output intensity of the excitation light as described in FIG. Since the efficiency is different (that is, there is a region having a linear tendency and a region having a saturation tendency), the difference appears by normalization, so that the emission peak of phosphorescence can be confirmed.

  Further, in order to extract only the emission peak of phosphorescence in the first data confirmed in the first normalized data shown in FIG. 5, the second normalized data is subtracted from the first normalized data, and the absolute By performing a calculation process that takes a value, only the emission peak of phosphorescence in the first data as shown in FIG. 6 can be obtained. Therefore, by using the above method, the emission peak of phosphorescence of the object to be measured can be detected accurately and easily.

  Note that the structure described in this embodiment can be applied not only to the phosphorescence measurement of NPB (abbreviation) described in this embodiment but also to the phosphorescence measurement of other organic compounds exhibiting fluorescence and phosphorescence. .

200 fluorescent phosphorescence measuring apparatus 201 light source 202 measurement sample 203 holder 204 beam splitter 205 objective lens 206 spectroscope 207 detector 210, 211 substrate 212 object to be measured 213 sealing material 214 space 400 area which tends to be saturated

Claims (4)

Sequentially irradiate two types of excitation light with different output intensities
Two types of data based on light emitted from the object to be measured are sequentially detected,
In each of the two types of data, two types of standardized data obtained by performing a standardization process based on the maximum emission intensity are calculated,
A phosphorescence measuring method, wherein a phosphorescence spectrum of the object to be measured is obtained from an absolute value of a difference between the two kinds of normalized data. Sequentially irradiate two types of excitation light with different output intensities
Two types of data indicating the emission intensity with respect to the wavelength of light emitted from the object to be measured are sequentially detected,
In each of the two types of data, two types of standardized data obtained by performing a standardization process based on the maximum emission intensity are calculated,
A phosphorescence measuring method, wherein a phosphorescence spectrum of the object to be measured is obtained from an absolute value of a difference between the two kinds of normalized data. Irradiating an object to be measured with first excitation light, detecting first data based on light emitted from the object to be measured;
Irradiating the object to be measured with second excitation light having an output intensity different from that of the first excitation light, and detecting second data based on light emitted from the object to be measured;
First normalization data obtained by performing standardization processing based on maximum emission intensity in the first data, and second obtained by performing normalization processing based on maximum emission intensity in the second data. A phosphorescence measuring method, wherein a phosphorescence spectrum of the object to be measured is obtained from an absolute value of a difference from the normalized data. Irradiating the object to be measured with the first excitation light, detecting first data indicating the emission intensity with respect to the wavelength of the light emitted from the object to be measured;
Irradiating the object to be measured with second excitation light having an output intensity different from that of the first excitation light, and detecting second data indicating emission intensity with respect to a wavelength of light emitted from the object to be measured;
First normalization data obtained by performing standardization processing based on maximum emission intensity in the first data, and second obtained by performing normalization processing based on maximum emission intensity in the second data. A phosphorescence measuring method, wherein a phosphorescence spectrum of the object to be measured is obtained from an absolute value of a difference in emission intensity with respect to a wavelength of light from the normalized data.

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