Two-photon spectroscopy of the (n,3s) Rydberg transition in acetaldehyde: The torsional sequence

Abstract

Eigenvalues and wave functions for acetaldehyde in its electronic ground state and the (n,3s) Rydberg state are calculated using the rho-axis method in combination with the high barrier approximation. The rotational structure of the first members of the torsional sequence in the two-photon spectrum is analyzed in terms of a zeroth-order rotation–torsional Hamiltonian. Combining experimental information on band positions and rotational contours, we determine the range of internal rotation constants and barrier heights, which is compatible with the experimental data. The analysis yields the following parameters: F=8.45±0.15 cm−1, V3=809±10 cm−1, ρ=0.33±0.03, ΘRAM=4.5°±0.8°, and APA=1.990 cm−1, BPA=0.330 cm−1, CPA=0.298 cm−1.

Photodissociation of Spatially Aligned Acetaldehyde Cations

“…In this report, parent ions were generated by 2+1 REMPI through the B 1 A ‘ state corresponding to the 3s ← n Rydberg transitions in the range from 354 to 363 nm. The wealth of spectroscopic knowledge for these Rydberg states − allows identification of the vibrational states of parent ions and thus provides a way to elucidate the effect of mode-selective vibrational excitation on cation photodissociation processes. Based on thermodynamic data taken from ref , four dissociation processes, leading to CH 3 CO + , HCO + , CH 4 + , and CH 3 + products, are energetically possible with four photons in this wavelength range (Figure ).…”

Two-Photon Spectroscopy of the Acetaldehyde−Ar Complex

“…Beside the spectroscopic interest, two-photon transitions of several molecular species are sufficiently strong to be employed for the state-specific product detection in molecular dynamics studies. − Another interesting candidate is acetaldehyde and its two-photon transition to the (n,3s) Rydberg state. − This two-photon transition is exceptionally strong due to a near resonance of the first excited-state S 1 with the virtual intermediate state. Recently, we were able to analyze the rotational structure of several observed bands including the torsional sequence. , …”

“…Recently, we were able to analyze the rotational structure of several observed bands including the torsional sequence. 14,15 As a stable intermediate in the oxidation of hydrocarbons, acetaldehyde represents an important air pollutant. 16 Subsequent reactions with both the hydroxyl radical and the nitrate radical result in the formation of peroxyacetyl nitrate, an important reservoir species for reactive nitrogen.…”