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Crystallographic dependence of the work function and volatility of LaB6
A224 Surface Science 107 (1981) 263-289 North-Holland Publishing Company
CRYSTALLOGRAPHIC DEPENDENCE OF THE WORK FUNCTION A N D V O L A T I L I T Y O F LaB6 L.W. S W A N S O N , M.A. G E S L E Y and P.R. D A V I S
Oregon Graduate Center, Beaverton, Oregon 97006, USA Received 6 October 1980; accepted for publication 24 December 1980
The crystallographic dependence of the work function as measured by thermionic and retarding methods has been determined for the (100), (110), (111), (346) and (321) crystal planes of LaB 6. According to the thermionic results the work function for the LaB 6 crystal increases in the sequence (346) < (100) < (110) < (111) and ranges from 2.41 to 2.90 eV. The LaB6 crystals of the same face, but 2% smaller interior B]La, exhibit 0.1 to 0.2 eV larger work function values. Retarding work function measurements confh-m the crystallographic dependence of thermionic work function except for the high index (346) plane which exhibits a considerably larger value when measured by retarding methods. The sequence of the work function increase for the low index planes is the same as the increase in surface B/La ratio as determined by Auger electron spectroscopy. Vaporization activation energies for atomic B vary with crystal face while the values for La are independent of crystal face.
Surface Science 107 (1981) 290-304 North-Holland Publishing Company EXPERIMENTAL AND THEORETICAL STUDY OF THE ANGULAR
RESOLVED SECONDARY ELECTRON SPECTROSCOPY (ARSES) FOR W ( l O 0 ) IN T H E E N E R G Y R A N G E 0 ~< E ~< 2 0 eV J. S C H , ~ F E R , R. S C H O P P E a n d J. H O L Z L
Fachbereieh Physik, University o f Kassel (Gesamthochschule), D.3500 Kassel, West-Germany and R. F E D E R
Theoretische Festkdrperphysik, FB 10, Universitdt Duisburg-GH, D-4100 Duisburg, West-Germany Received 23 October 1980; accepted for publication 15 January 1981 The angular resolved energy distribution of true secondary electrons emitted normal to a clean W(100) surface has been measured with a 180 ° Spherical Detlector Analyzer. While significant discrepancies are found with earlier secondary emission data, good agreement exists with angular resolved photoemission spectra. Comparison to recent band structure calculations (density of states effects) is made. The fine structure of the secondary emission spectrum is fully explained by numerical results obtained by means of a quantitative theory of angular resolved secondary emission. Further, the fine structure corresponds closely to reflection coefficient data.
CRYSTALLOGRAPHIC DEPENDENCE OF THE WORK FUNCTION A N D V O L A T I L I T Y O F LaB6 L.W. S W A N S O N , M.A. G E S L E Y and P.R. D A V I S
Oregon Graduate Center, Beaverton, Oregon 97006, USA Received 6 October 1980; accepted for publication 24 December 1980
The crystallographic dependence of the work function as measured by thermionic and retarding methods has been determined for the (100), (110), (111), (346) and (321) crystal planes of LaB 6. According to the thermionic results the work function for the LaB 6 crystal increases in the sequence (346) < (100) < (110) < (111) and ranges from 2.41 to 2.90 eV. The LaB6 crystals of the same face, but 2% smaller interior B]La, exhibit 0.1 to 0.2 eV larger work function values. Retarding work function measurements confh-m the crystallographic dependence of thermionic work function except for the high index (346) plane which exhibits a considerably larger value when measured by retarding methods. The sequence of the work function increase for the low index planes is the same as the increase in surface B/La ratio as determined by Auger electron spectroscopy. Vaporization activation energies for atomic B vary with crystal face while the values for La are independent of crystal face.
Surface Science 107 (1981) 290-304 North-Holland Publishing Company EXPERIMENTAL AND THEORETICAL STUDY OF THE ANGULAR
RESOLVED SECONDARY ELECTRON SPECTROSCOPY (ARSES) FOR W ( l O 0 ) IN T H E E N E R G Y R A N G E 0 ~< E ~< 2 0 eV J. S C H , ~ F E R , R. S C H O P P E a n d J. H O L Z L
Fachbereieh Physik, University o f Kassel (Gesamthochschule), D.3500 Kassel, West-Germany and R. F E D E R
Theoretische Festkdrperphysik, FB 10, Universitdt Duisburg-GH, D-4100 Duisburg, West-Germany Received 23 October 1980; accepted for publication 15 January 1981 The angular resolved energy distribution of true secondary electrons emitted normal to a clean W(100) surface has been measured with a 180 ° Spherical Detlector Analyzer. While significant discrepancies are found with earlier secondary emission data, good agreement exists with angular resolved photoemission spectra. Comparison to recent band structure calculations (density of states effects) is made. The fine structure of the secondary emission spectrum is fully explained by numerical results obtained by means of a quantitative theory of angular resolved secondary emission. Further, the fine structure corresponds closely to reflection coefficient data.