https://doi.org/10.1351/goldbook.L03473
Any technique in which a specimen is bombarded with a finely focused @[email protected] beam (diameter less than \(10\ \unicode[Times]{x3BC}\text{m}\)) in the @[email protected] or @[email protected] range under conditions of vapourization and thermal excitation of electronic states of sample material and in which the photon @[email protected] is observed.