Research On Raman Spectra Of Gas Medium By Femtosecond Laser Pulses

In this paper, the Raman scattering characteristics for CO₂, CH₄, C₂H₆ Barestudied by means of theory and experiment in pumping the gases with thefemtosecond laser.First. By Gaussian 03W method of the CO₂, CH₄, C₂H₆ Bthree kinds of molecularvibrational frequencies, using the procedures and the basic theory of molecularvibrational levels calculated vibrational levels of three elements, and plot of thequantum number 0,1 vibrational level diagram.Second. The repetition frequency 1000Hz, pulse width of 40fs, wavelength800nm, pump power 1700mw femtosecond laser pump the pressure 1MPa of CO₂,CH₄, C₂H₆ three gases, and the type spectroscope with SPEX1250 got three kinds ofgas The Raman emission spectrum. CO₂ gas at 1600nm has a richer spectrumDepartment; CH₄ gas in the 1543nm and 1604nm two strong intensity; C₂H₆ gas inthe 1546nm and 1605nm of the intensity of a strong, almost 2 times of CH₄ gas.Byexperimental observation of the different wavelengths of light intensity and lightsource of Raman pump power and the Raman gases CO₂, CH₄, C₂H₆ gas pressureand other parameters. In the experiment with the CH₄ gas pressure increasesobserved significant thermal defocusing effect; the same time as the pump powerincreased, CH₄ Raman intensity decreased significantly. C₂H₆ is stronyer in termsof stability and Raman intensity than CH4 according to the results in the papen.