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Title: Perturbation-facilitated detection of the first quintet-quintet band in C{sub 2}

The first high-spin transition in C{sub 2} (1 {sup 5}Π{sub u} − 1 {sup 5}Π{sub g}) is observed by perturbation-facilitated optical-optical double resonance spectroscopy. The experiment is performed by applying unfolded two-color resonant four-wave mixing. C{sub 2} radicals in the initial a {sup 3}Π{sub u}, v = 5 state are produced by using a discharge source in a molecular beam environment. The final quintet state is excited via intermediate “gateway” states exhibiting both substantial triplet and quintet character due to a perturbation between the 1 {sup 5}Π{sub g}, v = 0 and the d {sup 3}Π{sub g}, v = 6 states. Fifty seven rotational transitions in the P, Q, and R branches of all spin sub-states are measured and yield accurate molecular constants of the newly found upper level 1 {sup 5}Π{sub u}. In addition, satellite transitions (ΔJ ≠ ΔN) are observed and allow an accurate determination of the spin-orbit constant. The results are compared with high-level ab initio computations at the multi-reference configuration interaction level of theory. The high-lying quintet state is found to be predissociative and displays a shallow potential that accommodates three vibrational levels only.
Authors:
; ; ; ;  [1] ; ;  [2] ;  [1] ;  [3]
  1. Paul Scherrer Institute, CH-5232 Villigen (Switzerland)
  2. Laboratoire de Chimie Quantique, Institut de Chimie, Université de Strasbourg. 4, rue Blaise Pascal - CS90032 67081 STRASBOURG CEDEX (France)
  3. (Switzerland)
Publication Date:
OSTI Identifier:
22416225
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 9; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTROSCOPY; CALCULATION METHODS; COLOR; COMPARATIVE EVALUATIONS; CONFIGURATION INTERACTION; DETECTION; DISTURBANCES; FREQUENCY MIXING; MOLECULAR BEAMS; ORBITS; POTENTIALS; RADICALS; RESONANCE; SPIN; TRIPLETS; YIELDS