Absolute frequency measurement of the saturated absorption lines of methane in the 1.66 μm region

Atmospheric Absorption Parameters for Laser Propagation

“…[50] (mean discrepancy of 0.0012 ± 0.0005 cm" for 9 line positions), contrary to recent calculated results of Dijon (mean discrepancy of 0.067 L 0.053 cm-1 for 9 line positions). The probable explanation of this situation is that, for the moment, the calculation for the tetradecad region is inferior to good observations.…”

“…Concerning the 1.6-pm spectral region, comparisons between HITRAN, new calculations of Dijon, and results of Prof. Sasada's group [50], showed that the experimental results of HITRAN were in good agreement with Ref. [50] (mean discrepancy of 0.0012 ± 0.0005 cm" for 9 line positions), contrary to recent calculated results of Dijon (mean discrepancy of 0.067 L 0.053 cm-1 for 9 line positions).…”

Comb coherence-transfer and cavity ring-down saturation spectroscopy around 1.65 μm: kHz-accurate frequencies of transitions in the 2ν3 band of 12CH4

“…Saturation spectroscopy of the weak vibrational overtone and combination bands has been first demonstrated by Labachelerie and coworkers 15 using a modest finesse (F E 200) build-up cavity and its capability for sub-MHz absolute frequency calibration in combination with an OFC has been first reported by Ishibashi and coworkers. 16 However, only recent advances in laser technology and introduction of high sensitivity detection techniques, such as cavity ring-down spectroscopy (CRDS), make saturation spectroscopy attractive for a wide range of problems in high precision molecular spectroscopy and optical metrology. 6,[17][18][19][20][21][22][23][24][25][26][27] It is important to underline that application of high-finesse optical resonators for saturation spectroscopy demands laser radiation of high spectral purity.…”

Self- and air-broadened line shapes in the 2ν3 P and R branches of 12CH4

“…At the end, we obtained a final absolute calibration of our measured line positions using methane standards because the 2←0 HCl line centers were estimated to be less accurate [14]. For this, we considered two methane studies: (1) the positions of only two lines, R0 and Q1, by Ishibashi et al [41] who used the saturated absorption spectroscopy technique and, (2) the line positions of a much larger dataset by Zolot et al [42] who used comb-tooth resolved dual comb spectroscopy to obtain 1153 positions (and intensities) between 5870 and 6130 cm −1 ; of these, 46 lines had reported accuracies close to 0.2 MHz. Using the two methane transitions [41] changed the absolute calibration of our HCl-calibrated line centers by −0.00043 cm −1 , producing an overall multiplicative factor of 0.999999928(0.000000001).…”