Skip to main content
OSTI.GOVU.S. Department of Energy Office of Scientific and Technical Information
U.S. Department of Energy
Office of Scientific and Technical Information
 

The à 1Au state of acetylene: ungerade vibrational levels in the region 45,800–46,550 cm-1

Journal Article · · Molecular Physics
 [1];  [2];  [3];  [2];  [2];  [2]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Chemistry; MIT
  2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Chemistry
  3. Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, (Taiwan); Univ. of British Columbia, Vancouver, BC (Canada). Dept. of Chemistry
+ Show Author Affiliations
The ungerade vibrational levels of the à 1Au (S1-trans) state of C2H2 lying in the region 45,800-46,550 cm-1 have been assigned from IR-UV double resonance spectra. The aim has been to classify the complete manifold of S1-trans levels in this region, so as to facilitate the assignment of the bands of S1-cis C2H2. The rotational structure is complicated because of the overlapping of vibrational polyads with different Coriolis and Darling–Dennison parameters, but assignments have been possible with the help of predictions based on the properties of polyads at lower energy. An important result is that the analysis of the (1141, 1161) polyad determines the anharmonicity constants x14 and x16, which will be needed to proceed to higher energies. Some regions of impressive complexity occur. Among these is the band given by the 3361, K=1 state at 45,945 cm-1, where a three-level interaction within the S1 state is confused by triplet perturbations. Several probable S1-cis states have been observed, including cis-62, K=1; this vibrational level appears to show a K-staggering, of the type that arises when quantum mechanical tunnelling through the barrier to cis-trans isomerization is possible. The total number of identified cis vibrational states is now 6 out of an expected 10 up to the energies discussed in this paper.
Research Organization:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
FG02-87ER13671
OSTI ID:
1169176
Journal Information:
Molecular Physics, Journal Name: Molecular Physics Journal Issue: 21-22 Vol. 110; ISSN 0026-8976
Publisher:
Taylor & FrancisCopyright Statement
Country of Publication:
United States
Language:
English

References (23)

General introduction book January 1999
Excited states of acetylene: a CASPT2 study
  • Malsch, Karsten; Rebentisch, Rupert; Swiderek, Petra
  • Theoretical Chemistry Accounts: Theory, Computation, and Modeling (Theoretica Chimica Acta), Vol. 100, Issue 1-4 https://doi.org/10.1007/s002140050377
journal November 1998
The band system of acetylene journal September 1982
The band system of acetylene: Analysis of medium-wavelength bands, and vibration-rotation constants for the levels nν′3 (n = 4–6), ν′2 + nν′3 (n = 3–5), and ν′1 + nν′3 (n = 2, 3) journal May 1985
Spectroscopic constants for the 2.5 and 3.0 μm bands of acetylene journal June 1990
Symmetry-breaking collisional energy transfer in the 4νCH rovibrational manifold of acetylene: spectroscopic evidence of a quasi-continuum of background states journal June 2000
Zeeman quantum beat observed by IR–UV double resonance LIF spectroscopy of acetylene in the Ã1Au3ν3′+ν6′ and 3ν3′+ν4′ungerade vibrational states journal November 2001
Ab initio MO studies on the photodissociation of C2H2 from the S1 (1Au) state. Non-adiabatic effects and S-T interaction journal December 1996
Ab initio MO studies on the photodissociation of C2H2 from the S1(1Au) state. II. Mechanism involving triplet states journal July 1997
Conical intersections and strong nonadiabatic coupling effects in singlet-excited acetylene: An ab initio quantum dynamical study journal January 2008
Stretch-bend combination polyads in the Ã1Au state of acetylene, C2H2 journal August 2009
Extended permutation-inversion groups for simultaneous treatment of the rovibronic states of trans-acetylene, cis-acetylene, and vinylidene journal May 2011
IR−UV Double Resonance Spectroscopy of Acetylene in the à 1 A u n ν 3 ‘+ν 4 ‘ and n ν 3 ‘+ν 6 ‘ ( n = 2, 3) Ungerade Vibrational States † journal November 2000
The Bent Excited State of Acetylene journal June 1952
549. Excited states of acetylene. Part I. Possibilities of interaction between σ-bond hybridisation and π-electron excitation with resulting changes of shape during transitions journal January 1953
The valence-excited states T1–T4 and S1–S2 of acetylene: A high-level MR-CISD and MR-AQCC investigation of stationary points, potential energy surfaces, and surface crossings journal January 2003
Analysis of the Near Ultraviolet Absorption Spectrum of Acetylene journal May 1954
Darling–Dennison resonance and Coriolis coupling in the bending overtones of the ÃAu1 state of acetylene, C2H2 journal August 2008
Reduced dimension discrete variable representation study of cis–trans isomerization in the S 1 state of C 2 H 2 journal June 2011
Cis-trans isomerization in the S 1 state of acetylene: Identification of cis-well vibrational levels journal June 2011
The direct observation, assignment, and partial deperturbation of the ν 4 and ν 6 vibrational fundamentals in A ̃  1 A u acetylene (C 2 H 2 ) journal February 1993
The direct observation, assignment, and partial deperturbation of ν 5 and ν 3 +ν 5 in A ̃  1 A u acetylene (C 2 H 2 ) journal July 1993
Stationary points on the S 1 potential energy surface of C 2 H 2 journal July 1994

Cited By (3)

Probing the predissociated levels of the S 1 state of acetylene via H-atom fluorescence and photofragment fluorescence action spectroscopy journal November 2018
Generalized oscillator strengths of the low-lying valence-shell excitations of N 2 , O 2, and C 2 H 2 studied by fast electron and inelastic x-ray scattering journal March 2019
One-colour (∼220 nm) resonance-enhanced (S 1  − S 0 ) multi-photon dissociation of acetylene: probe of the C 2 A 1 Π u  −  X 1 Σ + g band by frequency-modulation spectroscopy journal February 2020

Figures / Tables (13)

Table 1(p. 26)table Table 1
Table 2(p. 29)table Table 2
Table 3(p. 29)table Table 3
Fig. 1(p. 30)figure Fig. 1
Fig. 2(p. 32)figure Fig. 2
Fig. 3(p. 33)figure Fig. 3
Fig. 4(p. 35)figure Fig. 4
Fig. 5(p. 36)figure Fig. 5
Fig. 6(p. 38)figure Fig. 6
Fig. 7(p. 39)figure Fig. 7
Fig. 8(p. 40)figure Fig. 8
Fig. 9(p. 42)figure Fig. 9
Fig. 10(p. 44)figure Fig. 10

Similar Records

Stretch-bend combination polyads in the Ã1Au state of acetylene, C2H2
Journal Article · Sun May 17 20:00:00 EDT 2009 · Journal of Molecular Spectroscopy · OSTI ID:1557819
Reduced dimension rovibrational variational calculations of the S1 state of C2H2. II. The S1 rovibrational manifold and the effects of isomerization
Journal Article · Sun Jan 12 19:00:00 EST 2014 · Journal of Chemical Physics · OSTI ID:1557648
Reduced dimension rovibrational variational calculations of the S{sub 1} state of C{sub 2}H{sub 2}. II. The S{sub 1} rovibrational manifold and the effects of isomerization
Journal Article · Mon Jan 13 23:00:00 EST 2014 · Journal of Chemical Physics · OSTI ID:22253603

Related Subjects

36 MATERIALS SCIENCE
acetylene
cis-trans isomerization
double resonance
perturbations
spectroscopy