Use of laser radiation in field-electron and field-ion microscopy for observation of biological molecules

An analysis is made of the possibility of using laser radiation in field-electron and field-ion projectors for the selective detachment of electrons or ions from macromolecules. It is proposed to photoionize selectively certain molecular bonds in macromolecules by a multistage process involving several laser pulses at different frequencies. A different laser variant of a field-ion projector is also considered: In this variant it is possible to reduce drastically the electric field intensity necessary for the field ionization of atoms in the imaging gas. It is proposed to use laser radiation in the excitation of atoms of the imaging gas to quantum states near the ionization threshold.