Origin of the Argon Nanocoating Shift in the OH Stretching Fundamental of n-Propanol: A Combined Experimental and Quantum Chemical Study

Abstract

Supersonic jet Raman spectroscopy reveals an increasing bathochromic shift of the OH stretching vibration in the most stable conformation of propanol with increasing extent of argon nanocoating. It falls short of the bulk matrix limit of 17 cm−1 even at large nozzle distances. Quantum chemical harmonic frequency calculations up to the CCSD(T) level show that this shift cannot be accounted for by individual Ar atoms or even a first solvation layer but instead requires several layers of Ar atoms around the molecule to be explained. It is shown that the stability of Ar−propanol clusters correlates with the number of close O and C contacts to the Ar and that bathochromic shifts are largely caused by backbone solvation. Hydrogen-bonding OH solvation tends to slightly increase the OH stretching frequency but is very sensitive to the computational level.

Ionization of Water Clusters Mediated by Exciton Energy Transfer from Argon Clusters

“…34,35 Finally we discuss the nature of the excitation process that is occurring in these mixed 16 The protonated cluster appearance energies agree well with those measured earlier 2 but the photoionization efficiency curve follows the shape of the argon cluster absorption spectrum quite dramatically. This is reflected in the enhancement of signal around 11.5 eV, peaking at 11.92 eV, dropping down and then rising again.…”

Probing the stiffness of the simplest double hydrogen bond: The symmetric hydrogen bond modes of jet-cooled formic acid dimer

“…Previous work 61 has shown that this leads to amorphous layers of Ar around the molecules. Figure 3 shows the result in the hydrogen bond fundamental range.…”

Incremental NH stretching downshift through stepwise nitrogen complexation of pyrrole: a combined jet expansion and matrix isolation study

“…5 Partial positive charges at the centre and negative charges at the molecule ends 6 lead to a more specific and directional guest-host interaction than for the similarly large argon host. 7 Stepwise nanocoating of hydrogenbonded organic compounds with matrix host molecules in supersonic expansions is a useful tool in understanding gas-to-matrix shifts [8][9][10] and may enable a more rigorous comparison of matrix isolation spectra to theoretical predictions.…”