Doppler-free infrared spectroscopy by opto-thermal detection

2001 Fiscal Year Final Research Report Summary

• Project/Area Number: 12440167
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Physical chemistry
• Research Institution: KYUSHU UNIVERSITY
• Principal Investigator: TANAKA Takehiko Faculty of Sciences, Kyushu University, Prof., 大学院・理学研究院, 教授 (00011586)
• Co-Investigator(Kenkyū-buntansha): HARADA Kensuke Faculty of Sciences, Kyushu University, Assistant, 大学院・理学研究院, 助手 (70165017) ; IMAJO Takashi Faculty of Sciences, Kyushu University, Assistant, 大学院・理学研究院, 助手 (40213227)
• Project Period (FY): 2000 – 2001
• Keywords: infrared diode laser sectrum / millimeter wave spectrum / laser photolysis / CoCO radical / vinyl radical

Research Abstract

The original project described in the proposal was to construct an apparatus for high-resolution spectroscopy utilizing a color-center laser, but became impracticable because of a fatal damage of the laser. Instead, we carried out the following high-resolution spectroscopic studies in line with the same purpose.
First, we constructed an apparatus for high-resolution LIF spectroscopy. The apparatus was tested by the observation of the B - X band of the NeBr_2 van der Waals complex using a cell with a pulsed supersonic nozzle. It was further tested by the observation at a resolution of 0.028 cm^<-1> of the A^2Σ-X^2Π band of the OH radical using a cell with a pulsed discharge nozzle. We hope that this apparatus may be developed for application to double resonance spectroscopy in which microwave and cavity ringdown techniques are combined.
Second, we have developed a new spectroscopic technique in which millimeter wave spectroscopy, pulsed supersonic jet, and excimer laser photolysis were co mbined. This technique was applied to observation of the spectrum of the vinyl radical. The in-plane CH bending vibration of this radical is governed by a double minimum potential, and the ground vibrational state is split into the "s" and "a" tunneling doublet. We observed tunneling-rotation transitions connecting the "s" and "a" states, as well as pure rotational transitions which occur within the "s" or "a" state. Precise knowledge on the double minimum potential, electron-spin-rotation interaction, electron-spin-nuclear-spin interactions.
Third, we observed the high-resolution vibration-rotation spectrum of the CoCO radical by infrared diode laser spectroscopy combined with excimer laser photolysis. The fundamental band of the CO stretching (ν_1) vibration, and hot bands starting from excited states of the bending (ν_2) and CoO stretching (ν_3) vibrations. Precise knowledge was obtained on the equilibrium structure and others. It was confirmed that this radical has the ^2Δ_i, electronic ground state. Millimeter wave spectrum was also observed yielding precise hyperfine interaction constants of the Co nucleus.