Time-Resolved Mass-Spectrometric Study on Infrared Laser Photodesorption of Ammonia from Cu(100)

Pulsed-infrared-laser time-of-flight mass spectrometry has been applied to investigate photodesorption of N${\mathrm{H}}_3$ adsorbed on a Cu(100) surface at 90 K. Desorption from monolayer and multilayer surface coverages due to resonant ${\nu }_s$ stretching vibrational excitation has been observed. Both single-photon and multiphoton excitation processes are examined and the molecule-surface interaction dynamics associated with the desorption phenomenon is discussed.