@article {2623,
	title = {Stretch-bend combination polyads in the (A)over-tilde(1)A(u) state of acetylene, C2H2},
	journal = {Journal of Molecular Spectroscopy},
	volume = {256},
	number = {2},
	year = {2009},
	note = {ISI Document Delivery No.: 478PDTimes Cited: 0Cited Reference Count: 55Steeves, Adam H. Bechtel, Hans A. Merer, Anthony J. Yamakita, Nami Tsuchiya, Soji Field, Robert W.},
	month = {Aug},
	pages = {256-278},
	type = {Article},
	abstract = {Rotational analyses are reported for a number of newly-discovered vibrational levels of the SI-trans; ((A) over tilde (1)A(u)) state of C2H2. These levels are combinations where the Franck-Condon active nu(2){\textquoteright} and nu(3){\textquoteright} vibrational modes are excited together with the low-lying bending vibrations, nu(4){\textquoteright} and nu(6){\textquoteright}. The structures of the bands are complicated by strong a- and b-axis Coriolis coupling, as well as Darling-Dennison resonance for those bands that involve overtones of the bending vibrations. The most interesting result is the strong anharmonicity in the combinations of nu(3){\textquoteright} (trans bend, a(g)) and nu(6){\textquoteright} (in-plane cis bend, b(u)). This anharmonicity presumably represents the approach of the molecule to the trans-cis isomerization barrier, where ab initio results have predicted the transition state to be half-linear, corresponding to simultaneous excitation of nu(3){\textquoteright} and nu(6){\textquoteright}. The anharmonicity also causes difficulty in the least squares fitting of some of the polyads, because the simple model of Coriolis coupling and Darling-Dennison resonance starts to break down. The effective Darling-Dennison parameter, K-4466, is found to increase rapidly with excitation of nu(3){\textquoteright}, while many small centrifugal distortion terms have had to be included in the least squares fits in order to reproduce the rotational structure correctly. Fermi resonances become important where the K-structures of different polyads overlap, as happens with the 2(1)3(1)B(1) and 3(1)B(3) polyads (B = 4 or 6). The aim of this work is to establish the detailed vibrational level structure of the S-1-trans state in order to search for possible S-1-cis ((1)A(2)) levels. This work, along with results from other workers, identifies at least one K sub-level of every single vibrational level expected up to a vibrational energy of 3500 cm(-1). (C) 2009 Elsevier Inc. All rights reserved.},
	keywords = {1AU, AB-INITIO MO, acetylene, Cis-trans isomerization, DISPERSED, DOUBLE-RESONANCE SPECTROSCOPY, FLUORESCENCE, FLUORESCENCE-SPECTRUM, INTRAMOLECULAR VIBRATIONAL REDISTRIBUTION, LASER-INDUCED, PARTIAL DEPERTURBATION, POLYATOMIC-MOLECULES, ROTATION CONSTANTS, STATE, vibration-rotation analysis, X BAND SYSTEM},
	isbn = {0022-2852},
	url = {<Go to ISI>://000268599300013},
	author = {Steeves, A. H. and Bechtel, H. A. and Merer, A. J. and Yamakita, N. and Tsuchiya, S. and Field, R. W.}
}
@article {2260,
	title = {Direct observation of the symmetric stretching modes of (A)over-tilde(1) A(u) acetylene by pulsed supersonic jet laser induced fluorescence},
	journal = {Molecular Physics},
	volume = {106},
	number = {15},
	year = {2008},
	note = {ISI Document Delivery No.: 371LATimes Cited: 1Cited Reference Count: 24Steeves, Adam H. Merer, Anthony J. Bechtel, Hans A. Beck, Annelise R. Field, Robert W.},
	pages = {1867-1877},
	type = {Article},
	abstract = {Rotational analyses are reported for the 2(0)(2) and 1(0)(1) bands of the (A) over tilde (1) A(u) <- (X) over tilde (1) Sigma(+)(g) transition of C2H2 near 45,000 cm(-1) (+2800 cm(-1) relative to T-0) from jet-cooled laser-induced fluorescence spectra. While the 220 band is unperturbed and straightforward to assign, the 1(1) level is strongly perturbed by interactions with the 2(1) B-2 polyad, where upsilon B{\textquoteright} = upsilon(4){\textquoteright} + upsilon(6){\textquoteright}. In order to assign the lines of this band, a population-labelling technique was used, employing an infrared laser to deplete the population in selected ground state rotational levels before probing with the ultraviolet laser. Deperturbation of the 1(1)/2(1) B-2 interaction leads to the value v(1){\textquoteright} = 2880.08 cm(-1) for the fundamental symmetric C-H stretching frequency. Assignments are also reported for the 2 3 and 1 1 2 1 levels, completing all assignments of levels containing excitation in only the totally symmetric vibrational modes up to + 4500 cm(-1). The reassignment of upsilon(1){\textquoteright} implies that some of currently accepted assignments above 47,000 cm(-1) are in error and suggests that the interpretation of some aspects of the near-threshold photodissociation measurements of Mordaunt et al. [J. Chem. Phys. 108, 519 (1998)] may need to be revisited.},
	keywords = {AB-INITIO MO, acetylene, ASSIGNMENT, C2H2, DEPERTURBATION, excited states, PARTIAL, PHOTODISSOCIATION, S-1((1)A(U)) STATE, SPECTROSCOPY, vibration-rotation analysis, VIBRATION-ROTATION CONSTANTS, vibrational spectroscopy, WAVELENGTH BANDS, X BAND SYSTEM},
	isbn = {0026-8976},
	url = {<Go to ISI>://000260831600004},
	author = {Steeves, A. H. and Merer, A. J. and Bechtel, H. A. and Beck, A. R. and Field, R. W.}
}
