Eine neue Untersuchung �ber die Banden des Silberhydrides

International audienceThe A 1Σ+ potential energy curve of AgH is studied by means of the second-order multistate multireference perturbation theory including the spin–orbit and relativistic effects. The anomalous behavior of the vibrational energy levels observed in experiment is reproduced well by theory. An analysis of the A 1Σ+ wave function shows that at the internuclear distance of 4–6 Å, a partial electron transfer from the 5pz orbital of silver to the 1s1s orbital of hydrogen occurs. This admixture of the ionic-like [core] 4d101s2H configuration occurring in A 1Σ+ due to two avoided crossings, namely X 1Σ+ with A 1Σ+ and A 1Σ+ with C 1Σ+, is found to be responsible for the unusual shape of the A 1Σ+ potential energy curve: the effective potential is a superposition of a Morse-like covalent interaction between Ag and H, and the electrostatic ionic-like interaction between Ag+ and H⎯. We present spectroscopic parameters, vibrational levels, and rotational constants computed for a large number of vibrational levels and observe good agreement with available experimental data. The equilibrium distance agrees within 0.01 Å and the vibrational frequency within 60 cm−1 for the state-specific calculations. Larger relative discrepancy is observed for ωexe, about 30 cm−1, however the non-Morse-like nature of the energy curve makes it impossible to describe the levels only with ω and ωexe,ωexe, so that direct comparison is not well defined

Section: Introductionmentioning

confidence: 82%

Theoretical study of the unusual potential energy curve of the A 1Σ+ state of AgH

Witek

Fedorov

Hirao

et al. 2002

“…[6][7][8][9][10][11] As the simplest silver hydride system, AgH has been well studied using spectroscopic and theoretical methods long ago. [12][13][14][15][16][17] The emission spectrum of AgH A 1 + →X 1 + was firstly reported by Bengtsson and Olsson,12 in which the relationship between the vibrational intervals of A 1 + and its high quantum numbers apparently deviates from the usual linear characteristic for Morse-like potentials. In the subsequent theoretical efforts, strong interactions among the electronic states were used to understand this anomalous behavior.…”

Section: Introductionmentioning

confidence: 99%

Probing the structural and electronic properties of AgnH− (n = 1–3) using photoelectron imaging and theoretical calculations

Xie

Xing

Liu

et al. 2012

Structural and electronic properties of silver hydride cluster anions (Ag n H − ; n = 1-3) have been explored by combining the negative ion photoelectron imaging spectroscopy and theoretical calculations. The photoelectron spectrum of AgH − exhibits transitions from AgH − 2 + to AgH 1 + and AgH 3 + , with the electron affinity (EA) 0.57(3) eV. For Ag 2 H − , the only observed transition is from Ag 2 H − (C ∞v ) 1 + to Ag 2 H (C 2v ) 2 A and the electron affinity is 2.56(5) eV. Two obvious electron bands are observed in photoelectron imaging of Ag 3 H − , which are assigned to the transitions from Ag 3 H − (C 2v -T, which means C 2v geometry with top site hydrogen) 2 B 2 to Ag 3 H (C 2v -T) 1 A 1 and Ag 3 H (C 2v -T) 3 B 2 . The electron affinity is determined to be 1.61(9) eV. The Ag-H stretching modes in the ground states of AgH and Ag 2 H are experimentally resolved and their frequencies are measured to be 1710(80) and 1650(100) cm −1 , respectively. Aside from the above EAs and the vibrational frequencies, the vertical detachment energies to all ground states and some excited states of Ag n H (n = 1-3) are also obtained. Theoretical calculations reproduce the experimental energies quite well, and the results are used to assign the geometries and electronic states for all related species.

“…It is well known that the A 1 ⌺ + state of AgH has an unusual or irregular behavior 3,6,7 and that the X 1 ⌺ + state is "well behaved." 12,14 The initial stage of our analysis therefore set out to determine the best possible models for the latter in a manner which was unbiased by any assumptions about the behavior of the former.…”

Section: A Treatment Of the X 1 ⌺ + Statementioning

confidence: 99%

“…Five years later Bengtsson and Olsson recorded an arc emission spectrum in which they observed 27 bands corresponding to vЉ͑X͒ ഛ 11 and vЈ͑A͒ ഛ 7. 3 They only reported band origins and upper-and lowerstate combination differences, but they were the first to notice the irregularities in the properties of the A state.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Direct-potential-fit analysis of new infrared and UV/visible AΣ+1-XΣ+1 emission spectra of AgH and AgD

Roy

Appadoo

Anderson

et al. 2005

New high-resolution infrared and UV/visible spectra of (107)AgH, (109)AgH, (107)AgD, and (109)AgD have been recorded with a Fourier transform spectrometer. The new line positions are combined with published microwave and older electronic A (1)Sigma(+)-X (1)Sigma(+) data and used, first in a decoupled analysis of the X state alone, and then in a global multi-isotopologue analysis which yields comprehensive descriptions of both the X (1)Sigma(+) and A (1)Sigma(+) states of all four isotopologues of AgH. While the A state was long believed to be heavily perturbed, it is shown that its irregular spectrum merely reflects an unusual potential function shape. A direct fit of all data to appropriate radial Hamiltonians yields analytic potential-energy functions and Born-Oppenheimer breakdown radial functions for the ground X (1)Sigma(+) and A (1)Sigma(+) states.