illustrated
Photonic Spectroscitation Photoacoustic Spectroscopy
principle
The sample absorbs light energy in a sample that is sealed in the photonic cell, and the sample is absorbed in the sample, and the release heat can be generated, and the release heat can be produced by the modulation frequency of the sample and the surrounding medium. Periodic heating, thereby causing a periodic pressure fluctuation, which can be detected by a sensitive microcontroller or piezoelectric ceramic microphone, and by amplifying the photonic acoustic signal, this is the photonic sound effect. If the incident mono-colored wavelength is variable, the photonic sound signal map variable as the wavelength can be measured, which is a photonic spectrum. If the light is a fine light that is focused, it can be recorded in the x - Y x - Y axis scanning mode, and the photonic sound signal can be recorded. This is the photonic imaging technology.
Instrument
The device of the photonic spectrum and its principle are shown in the figure. The incident light is a modulated monolithic light, and the optical intensity modulation can be used. The photocoya pool is a closed container, a sample and a microphone. As shown in the figure, a solid sample is carried out around the sample, and the gas medium that does not absorb light radiation, such as air. If a liquid or gas sample is used, the sample is filled with a photocoyum pool. The microphone should be very sensitive. For gas samples, the capacitive electret microphone is more suitable, which is equipped with an electronic detection system that can measure the heat of 10-6 ° C or heat input of 10-9 ocur / (cm 3 · second). For liquids and solid samples, a piezoelectric ceramic detector that is tightly in contact with the sample is preferably used.
[Note] Because the small mark cannot be displayed, "10-6 ° C" is "10-6 ° C" in the above means 10 is 6 times ; "10-9" means 10 negative 9 times square coke ; "cm 3" represents cubic centimeter .
Application
Since the photonic spectrum measurement is the size of the sample absorption light energy, the reflected light, scattering light, etc., the measured interference is small, so the photonic sound spectrum is suitable for measurement. Scatter samples, non-transparent samples, weak absorption samples and low concentration samples such as the incident light intensity, etc., and the sample can be measured by the crystal, powder, colloid, etc., which is unique to ordinary spectrum. . The photonic effect is related to the modulation frequency, and the modulation frequency can obtain information on different depth of the sample surface, so it is a non-destructive detection method for providing different depth structures in the surface.
Photonic acoustic spectroscopy is a product of spectral technology and quantitative thermal technology, which is a new method of detecting substances and research material properties in the early 1970s. The photonic sound technology is constantly evolving, and the carbon dioxide laser light source for gas analysis has emerged for the ultraviolet spectrometer for solid and liquid analysis, UV-visible photonic acoustic spectroscopy, and Fourier transform photoacoustic spectrometer. Photocondronic deflection spectroscopy, photonic laser microscope, laser thermal lens method and heat wave imaging technology are rapidly developing. Photonic sound spectroscopy is widely used in physical, chemistry, biology, medical, geology and material science.
Simple history
1880 A.G. Bell found solid light sound effects, 1881 he and J. Tindel and W.K. Lunqin successively found the photoso-sound effect of gas and liquid. They seal the gas in the pool, and ill be used to illuminate the pool in the sun, and they have heard some kind by answering a handset on the pool.
After the 1960s, due to the development of micro-signal detection technology, high-sensitive micro-tone and piezoelectric ceramic microphone emergence, strong light source (laser, xenon lamp, etc.), photonic sound effects and The study of the application is reunited. The photonic sound studies of a large amount of solid and semiconductor have found that the photonic spectrum is a very promising new technique.
Photonic sound technology is constantly evolving, the carbon dioxide laser light source infrared photonic spectrometer is suitable for gas analysis; xenon lamp UV-visible photonic spectrometer is suitable for analysis of solid and liquid; Fourier transform photocentricant spectrometer can be sample Provide a wealth of structural information. Photoelectric deflection spectroscopy, photocoleculate spectroscopy, photonic microscope, laser thermal lens method and heat wave imaging technology are rapidly developing.