Infrared spectra of formic acid clusters in noble gas matrices

•The first spectroscopic observation of formic acid clusters in noble gas matrices.•DFT calculations of several possible isomers for trimer and tetramer.•The observed clusters are assignable to two stable trimeric isomers.

Infrared absorption spectra of formic acid clusters (HCOOH)n have been observed in noble gas matrices (Ar, Kr and Xe). The concentration dependence of the spectra and a comparison with the assigned monomeric/dimeric bands has led to the assignment of polymeric species (HCOOH)n (n > 2). From comparisons of these spectra with several sets of DFT calculations, we concluded that the observed polymeric species can be assigned to stable isomers of (HCOOH)3.

Graphical abstractObserved vibrational peaks for formic acid clusters can be assigned to two stable isomers of (HCOOH)3, F309 and F310.Figure optionsDownload full-size imageDownload as PowerPoint slide