ABSORPTION SPECTRA OF ACETYLENE AND ACETYLENE-d$sub 2$ IN THE VACUUM ULTRAVIOLET
The absorption spectra of acetylene and acetylene-d/sub 2/ have been photographed at high dispersion in the 1250 to 1520A region. The vibrational structure of two Rydberg transitions at 85814 cm/sup -1/ (3R-A) and 74498 cm/sup - 1/ (3R'-A) previously reported by Price has been analyzed. Both of these transitions possess simple vibrational structure composed of only totally symmetric vibrations and must, therefore, be linear or very nearly so. However, a third transition (C-A) involving a trans-bent upper state has been found at 74747 cm/sup -1/ and, in addition, a fourth transition (B-A) at 74622 cm/sup -1/ involving a trans-bent and twisted upper state has been identified. The vibration identified in state 3R is (C/sub 2/H/sub 2/): nu /sub 2/( sigma /sub g/ ) = 1849 cm/s up -1/;, (C/sub 2/D/sub 2/): nu /sub 2/( sigma /sub g/) = 1720 cm/ sup -1/. Those in state 3R ' are (C/sub 2/H/sub 2/) nu /sub 1/( sigma /sub g/) = 2748 cm/sup -2/, nu /sub 2/( sigma /sub g/) = 1781 cm /sup -1/ and nu /sub g/ ( pi /sub g/) = 393 cm/sup -1/; (C/sub 2/D/sub 2/); nu /sub 1/( sigma /sub g/) = 2053 cm /sup -1/, nu /s ub 2/( sigma /sub g/) = 1559 cm/sup -1/ and v/sub 4/ ( pi /sub g/) = 302 cm/sup -1/. The four vibrations identified in state B are (C/ sub 2/H/sub 2/): nu /sub 1/(a/sub g/) = 2808 cm/sup -1/ nu /sub 2/(a/su b g/) = 1500 cm/sup -1/, nu /sub 3/(a/sub g/) = 759 cm/sup 01/ and nu /sub 5/(a/sub u/) =630 cm/sup -1/; (C/sub 2/D/sub 2/): nu /sub 1/(a/sub g/) = 2303 cm/sup -1/, nu / sub 2/(a/sub g/) = 1342 cm/sup -1/, nu /sub 3/(a/sub g/) = 635 cm/sup -1/ and nu /sub 5/(a/sub u/) = 438 cm/sup -1/. The nu /sub 4/(b/sub u/ vibration has als o been tentatively identified with magnitudes ~ 1880 cm/sup -1/ (C/sub 2/H/ sub 2/) and ~ 1100 cm/sup -1/ (C/sub 2/D/sub 2/). In state C two vibrations are identified with magnitudes (C/sub 2/H/sub 2/): nu /sub 2/(a/sub g/)=1751 cm/sup nu /sub 3/(a/sub g/) =434 cm/sup =-1/; (C/sub 2/D/sub 2/): nu /sub 2/(a/sub g/)= 1542 cm/sup -1/, nu /sub 3/(a/sub g/) = 385 cm/sup -1/. The moment of inertia I/ sub x/ is small in both B and C states causing sub-band separations of 10 to 100 cm/sup -1/. The rotational constants are: B ~ C ~ 1 cm/sup -1/. A ~ 7 cm/sup -1/ (C/sub 2/D/sub 2/ and ~ 8 cm/sup -1/ (C/sub 2/H/sub 2/) in both bent upper states. Vibrational data are given for all of the observed transitions. The identification of the observed states with some of those predicted by Mulliken is open to criticism. However, it is suggested that state C is Mulliken's A/sub u/, predicted to lie at 8.63 ev and state B is Mulliken's /sup 1/B/sub u/ (V/sub pi / ) which interacts with 3R' causing some nonlinearity in the latter. (auth)
- Research Organization:
- Univ. of Chicago
- NSA Number:
- NSA-12-015994
- OSTI ID:
- 4301626
- Journal Information:
- J. Mol. Spectroscopy, Vol. Vol: 2; Other Information: Orig. Receipt Date: 31-DEC-58
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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