Table 2. Band positions of the fundamentals v_i of cis-formic acid (in cm^–1) obtained in a supersonic jet expansion probed with Raman spectroscopy (this work) compared to literature values.

v i	Jet (this work)	Gas phase5	Shift a (cF–F)	Ar matrix b ,42	Matrix shift c
1	3637		+67	3617.2/3615.9	–21/–21
2	2873		–69	2899.5/2896.3	+27/+23
3	1818		+41	1808.0/1806.9	–10/–11
4				/1391.8
5				1243.4/1248.9
6	1093		–11	1107.3/1104.6	+14/+12
7				662.3/662.3
8
9		493.420509(7)	–147.30467(1)	502.9/505.3	–9.5/–11.9

^agas phase band position shifts from the trans- to the cis-rotamer.

^bsite 1/site 2 are two dominant trapping sites.

^cband position shift of the values of both matrix sites compared to the gas phase.