A detailed documentation of SPFIT and SPCAT files can be found here (accessed at 19.10.2021): https://spec.jpl.nasa.gov/ftp/pub/calpgm/spinv.pdf ____________________________________________________________________________________________________ ____________________________________________________________________________________________________ General remarks to "gauche-GS-v24.par", "gauche-GS-v24.lin", and "gauche-GS-v24.fit" files: used vibrational states v: v=0 is v = 0+ (short 0+) v=1 is v = 0- (short 0-) v=2 is v24= 1+ (short 24+) v=3 is v24= 1- (short 24-) ____________________________________________________________________________________________________ ____________________________________________________________________________________________________ Description of the gauche-GS-v24.lin file: J Ka Kc v J Ka Kc v Frequency unc weight // comment upper state | lower state ------------------------------------------------------------------------------------ 1 0 1 0 0 0 0 0 8462.9200 0.10 ... 28 4 25 0 27 4 24 0 236803.3004 0.02 2.2840 28 5 24 0 27 5 23 0 236803.3004 0.02 2.1873 28 5 23 0 27 5 22 0 236803.3004 0.02 2.1873 ... 2 1 1 0 1 1 1 1 16845.1700 0.10 // 0 - 1 Ka=1 ------------------------------------------------------------------------------------ excluded literature transitions from the final fit: EXP.FREQ. - CALC.FREQ. - DIFF. - EXP.ERR.- EST.ERR.-AVG. CALC.FREQ. - DIFF. - WT. v_obs-v_calc // R+C+D_1987: 5 0 5 0 4 1 3 1 18921.21000 18919.96738 1.24262 0.10000 0.00000 10 1 9 0 10 0 10 0 27218.97000 27214.01971 4.95029 0.10000 0.00000 12 1 11 1 12 0 12 1 29570.32000 29577.09753 -6.77753 0.10000 0.00000 // R+H+C_1988: 3 1 3 2 2 1 2 2 25198.83000 25198.72538 0.10462 0.10000 0.00000 3 1 2 3 2 1 1 3 25726.94000 25727.02535 -0.08535 0.10000 0.00000 3 1 2 2 2 1 1 2 25707.04000 25707.00258 0.03742 0.10000 0.00000 3 1 3 3 2 1 2 3 25231.94000 25231.79631 0.14369 0.10000 0.00000 4 2 2 2 3 2 1 2 33952.44000 33952.71037 -0.27037 0.10000 0.00000 <--- AC Stark shift - regressive 4 2 3 3 3 2 2 3 33975.02000 33974.73047 0.28953 0.10000 0.00000 <--- AC Stark shift - progressive 4 2 3 2 3 2 2 2 33945.02000 33944.79426 0.22574 0.10000 0.00000 <--- AC Stark shift - progressive 4 2 2 3 3 2 1 3 33982.40000 33982.74367 -0.34367 0.10000 0.00000 <--- AC Stark shift - regressive 4 1 3 2 3 1 2 2 34270.97000 34270.95308 0.01692 0.10000 0.00000 4 1 4 3 3 1 3 3 33643.05000 33642.99141 0.05859 0.10000 0.00000 4 1 3 3 3 1 2 3 34302.51000 34302.44873 0.06127 0.10000 0.00000 4 2 2 2 4 2 3 2 13.00000 11.86919 1.13081 0.10000 0.00000 11.94227 1.05773 0.5000 <--- blue detuned pumping 4 2 2 3 4 2 3 3 13.00000 12.01536 0.98464 0.10000 0.00000 11.94227 1.05773 0.5000 <--- blue detuned pumping 4 0 4 2 3 0 3 2 33925.04000 33925.02997 0.01003 0.10000 0.00000 4 0 4 3 3 0 3 3 33953.88000 33953.83881 0.04119 0.10000 0.00000 1 0 1 0 0 0 0 0 8462.92000 8462.77494 0.14506 0.10000 0.00000 8462.91291 0.00709 0.5000 1 0 1 1 0 0 0 1 8462.92000 8463.05088 -0.13088 0.10000 0.00000 8462.91291 0.00709 0.5000 2 0 2 0 1 0 1 0 16924.45000 16924.36506 0.08494 0.10000 0.00000 2 0 2 1 1 0 1 1 16924.85000 16924.91804 -0.06804 0.10000 0.00000 (Remark: The quality of transitions of Ref. [R+H+C_1988] was initially not secured, as no spectroscopic model to experimental accuracy was available and tunneling rotation interaction were not taken into account. Therefore, these transitions were omitted in the analysis, but many of them show nice agreement with the final fit. However, as the transition J',Ka',Kc' - J'',Ka'',Kc'' = 4,2,2 - 4,2,3 was presumably off-resonantly pumped (delta > 0, if delta = f_pump - f_0 with f_pump being the applied pump frequency and f_0 the resonance frequency), AC Stark shifts can explain the shift to a lower frequency in the regressive pump-probe 3-level arrangement when 4,2,2 - 3,2,1 is probed (v_obs-v_calc < 0) as well as the shift to higher frequency in progressive 3-level arrangement when 4,2,2 - 3,2,1 is probed (v_obs-v_calc > 0). This was observed for both substates. These transitions should be revisited before adding them to the line list. Comments: // P+S_1974 - H. M. Pickett, D. G. Scroggin, J. Chem. Phys. 61 (1974) 3954–3958. doi:10.1063/1.1681688 // R+C+D_1987 - Randell, A. P. Cox, H. Dreizler, Z. Naturforsch. A 42 (1987) 957–962. doi:10.1515/zna-1987-0908 // R+H+C_1988 - Randell, J. A. Hardy, A. P. Cox, J. Chem. Soc., Faraday Trans. 284 (1988) 1199–1212. doi:10.1039/F29888401199. // DR-Link - The assignment was verified by DM-DR measurements, but the center frequency is determined from conventional measurements // DR-Link - DM - This frequency was determined from DM-DR measurements (blended in conventional measurements) // A - The transitions frequency is assumed to be the A component (A and E component from internal rotation) // A+E - The transitions frequency is assumed to be a blend of A and E components (from internal rotation) // Average - The assignment of A and E is not secured (The average frequency of both components is used) // Int. Rot? - The line may be split by internal rotation (The second component is given additionally) // broad by int. rot.? - The line profile is assumed to be broadened due to unresolved splittings of the internal rotation // split Int A:B - Conspicious line shape of Delta_Ka=5 interaction: two features with intensity ratio A:B (center frequency uncertainty dv=100kHz; see Figure A4 of the supplemental material for mire information) // X - Y Ka=Z - Nominally forbidden transition from state Y to X, with Ka equal to Z. // X - Y Delta_Ka=4 - Nominally forbidden transition from state Y to X due to the Delta_Ka=4 interaction Used abbreviations: Double-modulation double-resonance - DM-DR unc - uncertainty