Pressure Measurement in XHV Region Using Nonresonant Multiphoton Ionization by Picosecond Pulsed Laser

By means of nonresonant multiphoton ionization using a picosecond pulsed YAG laser, pressure measurement for H2, CO and CO2 gases was carried out in the XHV pressure range. It was experimentally verified that pressure measurement was possible in the range of 10-11 Pa, and this pressure measurement method had pressure sensitivity of the same order of magnitude for the three molecules.