Study On Computer Assistant LIF Experimental System And Spectrum Of OH Radical

Supersonic molecular beam is one of the most important technique to get cold molecules with the temperature down to～1 K.At this low temperature regime,the Doppler broadening can be neglected,resulting in ultrahigh resolution spectrum which gives us the opportunity to study the hyperfine structure of molecules and the weak interaction of the molecules with an external field.Furthermore,the rotational spectrum can be greatly simplified due to the Boltzmann distribution of rotational population.On the other hand,supersonic molecular beam is also the source for further molecular Stark declaration.This thesis focused on the laser induced florescence(LIF) detection of the supersonic beam.To realize the computer assistant LIF experimental system,a program is composed in LabVIEW to control the laser system scanning,the data acquisition in a box-car and the data processing in a computer.To verify the reliability of this experimental system,the LIF spectra of hydroxyl radical(OH) are recorded both in frequency and time domains.In addition,the intermediate decomposed products of acetaldehyde(CH₃CHO) in an AC discharge have been diagnosed via concentration modulation spectroscopy. Some fragments,such as CO and CH,are spectrally studied to demonstrate the reducing of the parent pollution.