Far-infrared laser stark spectroscopy of CH3OH and13CH3OH

The high resolution laser Stark spectra of methanol and¹³C-substituted methanol have been studied up to Stark fields of about 60 000V/cm with the HCN and DCN lasers. Numerous families of absorption lines have been observed in both parallel and perpendicular polarizations. For methanol, the transitions J_k=7₅ 6₄ A,_t=0; J_k=11₄ 10₃ E_l,_t=0; and J_k=17₃ 16₂ E₂,_t=0 have been identified while the assignments for¹³C-substituted methanol are J_k=14₈ 15₇ A,_t=0; J_k=15₃ 14₂ A⁺,_t=0; J_k=10₇ 9₆ A,_t=0; and J_k=27₉ 27₈ E₁,_t=0. Zero-field frequencies for the assigned transitions are given with improved accuracy over those calculated from available molecular constants, especially for¹³CH₃OH.