Emission spectra and radiative lifetimes of the Cameron bands of CO trapped in solid rare gas matrices

Abstract

Articles you may be interested inIndirect dephasing model and librovibrational spectra of diatomics trapped in rare gas matrices. Application to the case of CO/Ar Absorption and emission spectra of Li atoms trapped in rare gas matrices Absorption and emission spectra of K atoms trapped in raregas matrices Absorption and emission spectra of Na atoms trapped in raregas matricesThe emission spectrum of the Cameron bands (a 3 n --+X 1 .l" +) of CO molecules trapped in solid Ne, Ar, and Kr has been studied using Xe resonance lamp excitation (A = 147 nm). The lifetime of the a 3n state has been measured in solid Ne and found to be 90 msec. The decay time of this state is exponential within the range of experimental errors. The lifetime has been calculated assuming spin-<>rbit mixing between '.l" + and 3n 0 states, and found to be 94 msec for J = O. The lifetime values in Ar and Kr matrices are found to be 7.2 and < I msec, respectively; this is consistent with the matrix shifts in solid Ne, Ar, and Kr, which for the ()...{) bands have been found to be -305, -946, and -2812 cm -I , respectively.

Ab initio relativistic treatment of the intercombination $a^3Π-X^1Σ^+$ Cameron system of the CO molecule

“…Furthermore, the FS-RCC a 3 Π Ω=0 + ,1 − X 1 Σ + TDM functions reproduce very well the distinguishable τ -values measured for the different Ω ± -components of the (0 ± ,3,2) level [9]. At the same time, the present τ estimates for the (0 + ,0,J ′ ) level are significantly higher than the experimental 90 ms obtained for CO molecules trapped in solid neon matrices [2]. This difference can be understood by bearing in mind the exponential decrease of the radiative lifetimes as J ′ -value increase, namely: τ = 690, 250, 115 and 65 ms for J ′ = 0, 1, 2 and 3 levels, The ab initio a 3 Π 0 + ,1 − X 1 Σ + electronic transition dipole moments evaluated using the different computational schemes: FS-RCC -fully relativistic Fock space coupled cluster method combined with the finite-field (FF) approach and generalized relativistic effective core potentials (GRPPs), RCI -large scale fully relativistic multi-reference configuration interaction method, SSI -scalar-state-interacting calculation based on the GRPPs exploiting, MCQR -multi-configuration quadratic response approach as implemented in Ref.…”

“…The radiative lifetimes evaluated by Eq. ( 6) for the particular rovibrational levels of the metastable a 3 Π 0 ± ,1,2 substates are compared with their experimental counterparts [2,4,8,9] in Table III. The complete tables of the ab initio FS-RCC, RCI and SSI transition dipole moments and resulting radiative lifetimes are tabulated in machine-readable format in the Supplemented Material (SM).…”

“…1). The upper triplet state is a metastable [2][3][4] since the spin-forbidden a 3 Π−X 1 Σ + electronic transition is extremely weak (its oscillator strength is only about 10 −7 -10 −8 [3,5]). Nevertheless, the Cameron bands are well observed in both absorption and emission spectra due to the regular spin-orbit coupling of the a 3 Π state with the remote singlet states manifold [6].…”

“…The intercombination (triplet-singlet) Cameron system has never been studied under fully relativistic approximation combined with state-of-art electron correlation treatment. To the best 1 † Dedicated to the memory of our colleague and teacher Dmitry Alexandrovich Varshalovich * avstol@phys.chem.msu.ru of our knowledge, ab initio studies of the a 3 Π − X 1 Σ + transition probabilities are limited so far by the multiconfigurational self-consistent field (MCSCF) quadratic response approach [5] or by using the spin-orbit coupling perturbation theory [2][3][4].…”

“…Comparison of the present theoretical and available experimental radiative lifetimes (in milliseconds) for the a 3 Π(Ω ± , v ′ , J ′ ) rovibronic levels of the 12 C 16 O isotopomer. a -Ref [2],. b -Ref [9],.…”