Patent ID: 8319178

Claim:
A mass spectrometry apparatus comprising: a substrate for mass spectrometry that is used in surface-assisted laser desorption/ionization mass spectrometry; a light irradiation means that irradiates a sample that is in contact with a surface of the substrate for mass spectrometry with measurement light to desorb an analyte contained in the sample from the surface of the substrate for mass spectrometry; a metal probe that generates near-field light at the leading end thereof by irradiation with the measurement light; a detector that detects the desorbed analyte; and an analysis means that performs mass spectrometry on the analyte based on a detection result by the detector, wherein the leading end of the metal probe is arranged in such a manner that the near-field light generated by irradiation with the measurement light is in contact with a measurement light irradiation portion of the sample, and when the angle formed between a line that perpendicularly connects the sample surface and the detector and a line that connects a laser beam irradiation position and two ends of a grid provided before a laser beam enters the detector is designated as α, and when the minimum angle formed between the line that perpendicularly connects the sample surface and the detector and a line that connects the leading end and a base portion of the metal probe is designated as β, the positional relationship α<β is established; wherein the metal probe includes a metal microparticle that is capable of inducing localized plasmons at the leading end thereof; and wherein the maximum diameter of the leading end is less than or equal to the wavelength of the measuring light.