TABLE II.
Experimentally determined parameters for ν22 and ν33 excited vibrational states of phenyl isocyanide (C6H5NC) compared to those for the ground state of phenyl isocyanide and the analogous excited states for benzonitrile (C6H5CN).
| Phenyl isocyanide | Phenyl isocyanide | Phenyl isocyanide | Benzonitrile39 | Benzonitrile39 | |
|---|---|---|---|---|---|
| ground state | ν22 (B1, 141 cm−1) | ν33 (B2, 155 cm−1) | ν22 (B1, 141 cm−1) | ν33 (B2, 163 cm−1) | |
| Av (MHz) | 5659.337 4(13) | 5 656.854 9(13) | [5 659.337 375 299] | 5 654.5(20) | 5 654.8(20) |
| Bv (MHz) | 1639.771 667(59) | 1 641.718 557(35) | 1 643.302 423(35) | 1 548.621 160(52) | 1 549.725 942(47) |
| Cv (MHz) | 1271.154 548(49) | 1 273.153 282(41) | 1 272.300 426(43) | 1 216.238 170(44) | 1 215.222 889(52) |
| ΔJ (kHz) | 0.0494 489(40) | 0.0502 869(36) | 0.050 738 4(40) | 0.045 995 0(27) | 0.046 171 5(27) |
| ΔJK (kHz) | 0.912 873(36) | 0.917 85(29) | 0.867 29(29) | 0.947 08(40) | 0.907 14(40) |
| ΔK (kHz) | 0.260 5(17) | [0.260 5]a | [0.2605]a | [0.242 3]a | [0.242 3]a |
| δJ (kHz) | 0.012 465 0(22) | 0.012 546 04(62) | 0.012 953 94(58) | 0.011 083 69(59) | 0.011 367 62(49) |
| δK (kHz) | 0.601 34(13) | 0.594 57(11) | 0.598 38(13) | 0.607 315(93) | 0.612 108(91) |
| ΦJ (Hz) | 0.000 002 62(17) | 0.000 002 82(12) | 0.000 002 80(14) | 0.000 001 166(86) | 0.000 000 675(89) |
| ΦJK (Hz) | 0.001 813 4(85) | 0.001 781 9(89) | 0.001 715 0(89) | 0.001 391 7(22) | 0.001 654 5(22) |
| ΦKJ (Hz) | −0.009 494(31) | −0.009 83(17) | −0.008 20(17) | −0.006 19(12) | −0.009 07(12) |
| ϕJK (Hz) | 0.000 855 5(58) | 0.000 778 4(51) | 0.000 761 7(58) | 0.000 749 3(41) | 0.000 672 7(42) |
| ΔE (MHz) | 290 266.50(10)b | 572 848.96(20)b | |||
| ΔE (cm−1) | 9.682 248(3) | 19.108 185(7) | |||
| Ga (MHz) | 9 718.593(13) | 9 532.0(62) | |||
| GaJ (MHz) | −0.005 836 3(44) | −0.004 588(27) | |||
| GaK (MHz) | −0.002 111 9(97) | ||||
| GaJJ (Hz) | 0.008 58(12) | ||||
| GaJK (Hz) | −0.076 0(27) | ||||
| Fbc (MHz) | −0.480 985(59) | −0.411(39) | |||
| FbcK (kHz) | −0.015 20(20) | −0.009 81(44) | |||
| Δi (uÅ2) | 0.073 921(28) | −0.223 933(25) | 0.378 085(15) | −0.191(32) | 0.393(32) |
| Nc | 4 723 | 3 727 | 3 627 | 3 001 | 2 933 |
| σ (MHz)d | 0.034 | 0.040 | 0.040 | 0.034 | 0.037 |
ΔK, along with all sextic and octic centrifugal distortion constants not listed explicitly, were fixed at the ground state values of the corresponding molecule from Table I.
ΔE, Ga, , , , , Fbc, and parameters are for coupling between the ν22 and ν33 vibrational states of the corresponding molecule.
Number of fitted transition frequencies.
Deviations for the two vibrational state subsets: the overall standard deviation of the coupled fit for phenyl isocyanide to 7354 lines is 0.040 MHz and for benzonitrile to 5934 lines is 0.036 MHz.