Induced Fluorescence and Temperature Jump in CO2 by Resonant Absorption of 10.6‐μ CO2 Laser Radiation

摘要

Experimentally observed ``jump'''' phenomena in gas temperature and detected fluorescence at a well‐defined pressure, when a 50‐W beam of focused 10.6‐μ laser radiation is absorbed in CO2, are reported. A model based on sufficiently fast relaxation of (00°1) vibrational‐translational energy and sufficiently slow energy loss out of the laser focus to result in a runaway of temperature is proposed to account qualitatively for the observed features. Calculation of the temperature jump (160°C) agrees with a measured value and establishes the reason for the order‐of‐magnitude jump in detected fluorescence by means of an increased Boltzmann distribution of absorbing states. The influence of helium on the jump condition was established; in particular, the helium quenching effect via increased thermal conductivity supports the proposed model.