Photodesorption of carbon monoxide from polycrystalline nickel

The photodesorption of carbon monoxide from polycrystalline nickel ribbons was investigated using light of ultraviolet and visible wavelengths. Ultrahigh vacuum techniques and mass spectrometric detection were utilized in these measurements. The ribbons were prepared both by the high temperature outgassing method and by argon ion bombardment. On the argon-ion-bombarded surfaces carbon monoxide surface coverages were 2–3 orders of magnitude larger than the coverages measured on outgassed surfaces. From both types of surfaces photodesorption was predominately a bulk heating effect, whereas local heating and/or quantum effects were negligible. The validity of this conclusion was demonstrated for a wide variety of pressures, wavelengths, and light intensities.