Possibility of resonant three-photon isotope-selective excitation of vibrational states with υ = 3 of the UF₆molecule mode ν₃by radiation from two pulsed IR lasers in a gas-dynamically cooled molecular flow

Abstract

We consider the possibility of resonant isotope-selective population of states with υ = 3 of the vibrational mode ν 3 of UF6 molecules as a result of three-photon bichromatic excitation of the molecules by IR radiation from two pulsed CF4 lasers and two pulsed para-H2 lasers. We propose specific schemes and analyse the possibility of exciting the 238UF6 and 235UF6 molecules into states with υ = 3 of the vibrational mode ν 3 using two CF4 lasers (or para-H2 lasers) generating in the region of 16 μm at frequencies that are significantly (by ∼3.5 – 17 cm−1) detuned from the linear absorption bands at the frequencies of ν 3 vibration of these molecules in a gas-dynamically cooled molecular flow. However, the sum of the doubled lasing frequency 2ν L1 of the first laser and the frequency ν L2 of the second laser is equal to a frequency of the transition υ = 0 → υ = 3 of the vibrational mode ν 3 of the UF6 molecules. When both laser pulses coincide in time, the possibility of selective excitation of UF6 molecules from the ground vibrational state with υ = 0 to the state with υ = 3 of the vibrational mode ν 3 is realised. The proposed schemes for the excitation of UF6 molecules to states with υ = 3 are compared with the previously implemented schemes for the effective excitation of states with υ = 3 of the vibrational mode ν 3 (F 1) and states with υ = 2 of the vibrational mode ν 3 (A 1) of SF6 molecules by three- and two-frequency radiation of pulsed CO2 lasers, respectively.