DOUBLE-RESONANCE MEASUREMENTS OF VIBRATIONAL LEVELS POPULATED BY INFRARED MULTIPHOTON EXCITATION OF CF3I IN A MOLECULAR-BEAM

The infrared multiphoton excitation of CF3I by CO2 laser radiation bet ween 1068 and 1082 cm-1 (9R4 to 9R26 lines) is monitored under collisi on-free conditions by (2 + 1) resonance-enhanced multiphoton ionizatio n through the C state. The vibrational levels populated are measured a s a function of infrared laser frequency. The vibrational level resona nt at the first absorption step is seen only partially to determine wh ich higher combinations are populated. Population of vibrational level s up to four times the infrared photon energy is seen, with no discern ible transitions from levels with a higher vibrational energy. The res ults are consistent with previous reports of bimodal energy distributi ons in CF3I.