Studies on New Spectrometric Light Source -Rainbow Stars-

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Two-color stimulated Raman emission was generated by introduction of a two-color laser beam into pressurized hydrogen, in order to obtain widely-tunable laser emission. The laser wavelength could be changed from 247 to 771 nm. However, it was technically difficult to simultaneously scan both the laser wavelengths. Then, a few numbers of rotational stimulated Raman lines were first generated by introduction of a circularly-polarized, single-color laser beam. Succeedingly, the polarization was changed to a linear, and many rotational and vibrational lines were generated by the two-color stimulated Raman effect. This technique allows a wavelength scan and is useful for analytical spectroscopy. It was also possible to generate either vibrational or rotational lines selectively by optimizing the polarization of the beam. the pressure of hydrogen, and the beam focusing condition. Alternatively. the separation of the rotational lines could be changed from 587 to 354 cm^<-1> by replacing ortho … More -hydrogen with para-hydrogen. This approach is useful to increase the density of the rotational lines in the specified spectral region.Equally-spaced, multi-frequency laser emission can, be generated by two-color stimulated Raman emission. As is known from Uncertainty principle, ultrashort light pulses can be generated by the laser with wide frequency components. Then, the presented approach might give a break-through in generation of ultrashort pulses. Theoretical and preliminary experimental works were performed in this study. By a theoretical calculation, a laser pulse with several fs could be generated, when the laser beam was Fourier-transform limited and was modelocked. Several optical configurations for generation of ultrashort pulses were proposed, e. g. a quenching laser/short-cavity laser/distributed feedback laser/exciter laser amplification/two-color stimulated Raman emission. - In our preliminary study, a 2-ns laser pulse was generated by quenching the long tail of the dye laser pulse. It was verified that a high-power, sh(Yrt-pulse laser is useful for efficient generation of two-color stimulated Raman emission. The multi-pass Raman cell developed in our laboratory was useful for reduction of threshold and improvement of the efficiency.Two-color stimulated Raman emission was used as a light source for excitation of the sample in a condensed phase and in a supersonic jet. Thus it was verified to be useful for measurement of the sample in analytical spectroscopy. Less