Frozen matrix-assisted laser ablation followed by resonance-enhanced multiphoton ionisation coupled with reflectron time-of-flight mass spectrometry was applied to the detection and spectroscopic study of biological molecules dissolved in different solutions. When ablated by CO₂ laser radiation, the analyte molecules were ionised with a tuneable dye laser or an ArF excimer and detected by a microchannel plate assembly.

The cooling and expansion characteristics of the method were examined when the molecules of tryptophan and tyrosine were ablated from a frozen solution of ethanol mixed with glycerin. The resonantly enhanced two-photon ionisation spectra of amino acids obtained by collecting the signal at masses of molecular ions with only minimal fragmentation revealed the cold, sharp features. From the rotational contour of the electronic origin of the S₀-S₁ transition of laser-ablated tryptophan and tyrosine, rotational cooling appear to be comparable with that of the molecules when they were ablated from a solid surface and entrained into a supersonic jet of a carrier gas. The expansion and fragmentation peculiarities of the ablated molecules depending on the ablating and the ionising laser intensity were studied.

The capabilities of the technique are demonstrated in the detection of the molecules of fulerene C₆₀ and gramicidin-D ablated from frozen benzene and aqueous solution, respectively.