SONDHEIMER OSCILLATIONS AS A TECHNIQUE FOR SURFACE SCIENCE

For the first time Sondheimer oscillations (SO) have been used to inve stigate processes occurring during deuterium interaction with the W(10 0) face under UHV conditions within the temperature range from 4.2 to 2500 K. SO are oscillations of single-crystal plate magnetoresistance arising at helium temperatures as the strength of the magnetic field p erpendicular to the plate surface is increased. The technique exploits the high sensitivity of surface scattering of conduction electrons to submonolayer adsorption and symmetry changes of the adsorbed layer. F ourier transformation analysis of the oscillations measured at differe nt adsorbate coverages deposited at 4.2 K (0 < theta < 1) has shown th at the submonolayer deuterium film symmetry at theta = 1 repeats proba bly the clean W(100) symmetry (theta = 0) but at theta = 0.5 the adsor bate film is disordered. Annealing of the film deposited at 4.2 K with in the temperature range from 4.2 to 900 K results in adsorbate desorp tion and ordering influencing the SO parameters.