Tunable mid-infrared spectrometer based on KTA crystal to study fundamental nu(3) band of methane

Tunable mid-infrared radiation in the range 3-3.5 mum have been generated b y difference frequency mixing in a biaxial potassium titanyl arsenate (KTA) crystal. The fundamental input radiations are the second harmonic of a com mercially available Nd:YAG laser radiation (i.e. 532 nm) and the same pumpe d visible dye laser radiation. Using the generated tunable radiation the ro om temperature absorption spectra of R-branch of the nu (3) band of methane at 120 mbar pressure have been studied. Pressure dependent absorption of P (7) line of the nu (3) band of methane have also been studied. The absorpti on measurements have been performed in an indigenously built single pass ga s cell of length 33 cm.