Assignment of iodine BX lines by resonant coherent anti‐stokes Raman spectroscopy

Abstract

AbstractA resonant CARS scheme is described, which allows the examination of the I2 spectrum for discrete and continuum resonances simultaneously. This is the first time such a method of excitation for molecular species has been demonstrated. The absence of P and R branches determined by double resonances with the signal and the pump frequencies makes the assignment easier. It is possible to record all the Raman lines of O, Q and S types, whereas for continuum CARS mainly S lines are detected. The proposed technique makes the spectral structure clearer and the identification simpler. When the temperature of I2 vapour is increased to 330 K, some new Raman lines, the sixth and seventh overtones, are obtained, because of population of higher excited vibrational states. The variation of the anti‐Stokes signal Ia with iodine vapour pressure has also been investigated.