A method of laser ablating a thin film of a liquid biosample that prevents production of ablation recoil products and that facilitates analysis of an ablation plume from the thin film, comprising: preparing the thin film of the liquid biosample: providing a substrate having a flat surface, and providing a cover having a flat surface, providing one of said substrate or cover with a plurality of spacers,, having a preselected thickness disposed on its flat surface such that, said substrate and the cover are aligned and mated with their respective flat surfaces, facing each other, said substrate and the cover are separated by a distance equal to the preselected thickness of said plurality of spacers,,; depositing a sample volume of the liquid biosample on the flat surface of the substrate; mating the cover with the substrate to sandwich the sample volume of liquid biosample between their respective flat surfaces,; and securing the substrate in relation to the cover, thereby spreading the sample volume of the liquid sample into a liquid layer between the respective flat surfaces,, the liquid layer comprising a thickness approximating the preselected thickness of said plurality of spacers,,; cooling the substrate and the cover to a temperature below a freezing point of the liquid biosample, thereby freezing the sample volume of the liquid biosample, wherein cooling comprises initiating nucleation of the sample volume by creating a controllable disturbance thereto, thereby providing a reproducible freezing temperature thereof, wherein freezing comprises a supercooling phase, and thereby freezing the thin film by approximating the preselected thickness of said plurality of spacers,,; removing the cover to expose the thin film; irradiating the thin film with a laser pulse from a pulsed infrared laser, said preselected thickness of the frozen thin film of sample is selected such that an absorption length of light emitted by the pulsed laser in the frozen thin film of sample is of the order of the preselected thickness of the plurality of spacers,, and wherein the laser wavelength is corresponding to a dominant molecular vibrational transition in the thin film, wherein an enthalpy density within an excited portion of the thin film immediately after a laser pulse absorption is greater than an enthalpy of vaporization, thereby releasing the ablation plume from the thin film, thereby preventing production of ablation recoil products. preparing the thin film of the liquid biosample: providing a substrate having a flat surface, and providing a cover having a flat surface, providing one of said substrate or cover with a plurality of spacers,, having a preselected thickness disposed on its flat surface such that, said substrate and the cover are aligned and mated with their respective flat surfaces, facing each other, said substrate and the cover are separated by a distance equal to the preselected thickness of said plurality of spacers,,; depositing a sample volume of the liquid biosample on the flat surface of the substrate; mating the cover with the substrate to sandwich the sample volume of liquid biosample between their respective flat surfaces,; and securing the substrate in relation to the cover, thereby spreading the sample volume of the liquid sample into a liquid layer between the respective flat surfaces,, the liquid layer comprising a thickness approximating the preselected thickness of said plurality of spacers,,; providing a substrate having a flat surface, and providing a cover having a flat surface, providing one of said substrate or cover with a plurality of spacers,, having a preselected thickness disposed on its flat surface such that, said substrate and the cover are aligned and mated with their respective flat surfaces, facing each other, said substrate and the cover are separated by a distance equal to the preselected thickness of said plurality of spacers,,; depositing a sample volume of the liquid biosample on the flat surface of the substrate; mating the cover with the substrate to sandwich the sample volume of liquid biosample between their respective flat surfaces,; and securing the substrate in relation to the cover, thereby spreading the sample volume of the liquid sample into a liquid layer between the respective flat surfaces,, the liquid layer comprising a thickness approximating the preselected thickness of said plurality of spacers,,; cooling the substrate and the cover to a temperature below a freezing point of the liquid biosample, thereby freezing the sample volume of the liquid biosample, wherein cooling comprises initiating nucleation of the sample volume by creating a controllable disturbance thereto, thereby providing a reproducible freezing temperature thereof, wherein freezing comprises a supercooling phase, and thereby freezing the thin film by approximating the preselected thickness of said plurality of spacers,,; removing the cover to expose the thin film; irradiating the thin film with a laser pulse from a pulsed infrared laser, said preselected thickness of the frozen thin film of sample is selected such that an absorption length of light emitted by the pulsed laser in the frozen thin film of sample is of the order of the preselected thickness of the plurality of spacers,, and wherein the laser wavelength is corresponding to a dominant molecular vibrational transition in the thin film, wherein an enthalpy density within an excited portion of the thin film immediately after a laser pulse absorption is greater than an enthalpy of vaporization, thereby releasing the ablation plume from the thin film, thereby preventing production of ablation recoil products.