A study of the methanol laser with a 500 MHz tunable CO2 pump laser

The absorption spectrum of CH₃OH is measured optoacoustically over a 500 MHz tuning range in 84 different CO₂ laser lines, and 19 assigned CO-stretch absorptions are used for establishing the linearity of the measurements over two decades of absorption coefficient. 40 new FIR laser lines originating from large offset absorption, are reported in the wavelength range between 40 and 400 m, and their wavelengths are given with a relative accuracy of 5×10^–5. 30 lines are assigned, involving CO-stretch transitions in torsionaln=0, 1, and 2 states, as well as transitions inn=3 of the vibrational ground state, pumped by transitions to Fermi interacting states.Work supported by the Danish National Science Research Council grant No. 11-5375