Doppler‐free saturation spectroscopy of polyatomic molecules: Photochemical hole burning of gas phase s‐tetrazine

摘要: Doppler‐free spectra of two vibronic bands in the A (1B3u)←X (1Ag) transition photochemically instable s‐tetrazine (H2C2N4) are presented. For first time saturation spectroscopy is successfully applied to a large polyatomic molecule. Photochemical decomposition molecules takes place after excitation and prevents molecule from returning ground state by radiation nonradiative processes. This represents particular type hole burning velocity distribution. The elimination inhomogeneous Doppler broadening enables us determine collisionless homogeneous linewidths. 0–0 band value γ=190 MHz found whereas 16a11 at higher excess energy (ν’16a =256 cm−1) shows sharper linewidth γ=140 MHz. No rotational dependence up J levels than 70. It argued that internal conversion X (1Ag) process responsible for observed linewidths diss...