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Hitachi High-Technologies GLOBAL

Measurement example for a fluorescence spectrum

In a measurement, various components, including Raman scattered light, the fluorescent light of both the solvent and specimen, and secondary light of excitation are mixed with the excitation light.


1) Sensitivity Used to indicate system performance. Generally, this quantity is expressed by a signal to noise ration.
2) Xenon lamp Light source used for excitation
3) Fluorescent light Light emitted by the excited specimen.
4) Unit of fluorescence intensity Relative intensity; no units
5) Fluorescent detector Detector for measuring the intensity of emission. A photomultiplier tube (photomul) is commonly used.
6) Fluorescence spectrum Spectrum obtained by measuring the fluorescence wavelength
7) Detection limit Concentration of the most dilute specimen which can be measured. This limit depends on the specimen.
8) Calibration curve Graph for converting fluorescence intensity into concentration.
9) Photomultiplier tube → fluorescence detector
10) Measurement of intracellular Ca2+ concentration One example of the application of the fluoroscopic method. The time changes at two or more wavelengths are measured simultaneously.
11) Three-dimensional measurement A fluorometry technique using three axes: excitation wavelength, fluorescence wavelength, and fluorescence intensity. The output data contains much information.
12) Scanning The successive shifting of the wavelength of a spectroscope to obtain a spectrum, or the resulting measurement.
13) Stokes’ Law The principle that the fluorescence wavelength is longer than the excitation wavelength.
14) Spectrum correction Measurement with processing to compensate for the characteristics of the specific system used.
15) Slit The slit at the entrance of the spectroscope. This determines the resolution of the spectrum.
16) Instrumental function The characteristics of the specific system
17) Secondary light Light which appears at a wavelength twice that of the light entering spectroscope. For example, if light at a wavelength of 300 nm enters the spectroscope, secondary light will appear at 600 nm. 12
18) White light Light with various wavelength components (sunlight or light of a xenon lamp).
19) Wavelength Number corresponding to the color (energy) of light; commonly expressed in nm (nanometer) nm.
20) Wavelength scanning → Scanning
21) Bandpass → Resolution
22) Resolution Indicatedsthe most narrow peak that can be measured.
23) Raman scattering A type of scattered light which appears when materials are irradiated.
24) Phosphorescence A type of emission. Even if the excitation light is cut off, the light due to phosphorescence will gleam longer than the fluorescent light.
25) Excitation source → Xenon lamp
26) Excited state State in which a specimen has absorbed energy.
27) Excitation spectrum Spectrum obtained by scanning the wavelength of the excitation light. This spectrum resembles an absorption spectrum.
28) Response Index which weakens the output data. A number suitable for the scanning speed must be chose.
29) Excitation light Light used to excite a specimen.