{'fraction_non_alphanumeric': 0.031294452347083924, 'fraction_numerical': 0.01422475106685633, 'mean_word_length': 5.901960784313726, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Electronic promoters and semiconductor oxidation: Alkali metals on Si(111) surfaces.

We examine the effect of thin (1\char21{}2 monolayers) overlayers of the low-electronegativity metals Cs and Na upon the oxidation of Si(111) surfaces. Synchrotron-radiation photoemission studies of oxygen chemisorption as a function of overlayer thickness and oxygen exposure indicate large oxidation-promotion effects and the formation of Si oxide phases where high Si oxidation states dominate. Comparison with promotion effects induced by transition-metal and noble-metal overlayers forces, for alkali metals, a reevaluation of the microscopic mechanisms proposed to explain overlayer-induced oxidation promotion.