{'fraction_non_alphanumeric': 0.02345159350571257, 'fraction_numerical': 0.019242333132892364, 'mean_word_length': 4.602693602693603, '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}}
Photon Stimulated Desorption of Ions From Water and Methanol Adsorbed on a Ti(0001) Surface

Synchrotron radiation (15 ≲ hν ≲ 75 eV) has been used to study ion desorption from water and methanol adsorbed on a Ti(0001) surface, in an effort to understand ion desorption from covalently bonded systems. Both water and methanol dissociate at all coverages upon adsorption on Ti at 300 K. Using variable wavelength UPS, the adsorbed fragments OH, O and H are identified for water and CH3O, C, O and H for methanol. At 90 K, dissociation occurs initially to yield the same products, while at higher exposures, condensed overlayers are formed. PSD of ions from the two adsorbates show very different behaviour. In the water experiment, ion desorption originates from the dissociated species at both 300 and 90 K. H+ emission from dissociated water is corelated with the presence of OH on the surface while ion desorption from the ice multilayer is almost an order of magnitude less. In contrast, ion emission from the dissociated methanol is immeasureably low in our instrument while a large H+ signal is observed from the condensed layer. It is obvious that different molecular states are involved in the ion desorption in these cases. The H+ emission from OH appears to be correlated with the O 2s level near 25 eV and the Ti 3p core level near 33 eV. However, ion desorption could arise strictly from different localized two hole states in OH. The H+ observed from methanol appears to be initiated by ionization of the 4a' orbital with an onset near 18 eV. Using isotopic labeling experiments, it is shown that H+ originates from the methyl group rather than the OH.