Double resonance measurements of far-infrared lasing transitions in methanol

摘要

Abstract: In this work, precise frequencies were measured for two important far IR (FIR) laser transitions in methanol optically pumped by the 9P(16) CO$-2$/ laser line at an offset of $PLU@64 MHz from the line center, using IR - millimeter wave double resonance technique. The two measured FIR frequencies are at 525,427.902 and 477,790.879 MHz, with an estimated precision of $POM kHz. In addition another frequency was measured at 573,025.151 MHz, and this line corresponds to an absorption transition whose lower level is the upper pumped level. The measurements provide valuable confirmation for the assignments of the IR as well as the FIR transitions. In addition, we also measured accurate frequencies for several transitions in the ground vibrational state in the range 109-127 GHz. !20