Metallic Indium and its oxides are useful in electronics applications in transparent conducting electrodes, as well as in electrocatalytic applications. In order to understand more fully the speciation of the indium and oxygen composition of the indium surface exposed to atmospheric oxidants, XPS, HREELS, and TPD were used to study the indium surface exposed to water, oxygen, and carbon dioxide. Clean In and authentic samples of In 2 O 3 and In(OH) 3 were examined with XPS to provide standard spectra. Indium was exposed to O 2 and H 2 O, and the ratio of O 2to OHin the O1s XPS region was used to monitor oxidation and speciation of the surface. HREELS and TPD indicate that water dissociates on the indium surface even at low temperature, and that In 2 O 3 forms at higher temperatures. Initially, OH-is the major species at the surface. Pure In 2 O 3 is also OH-terminated following water exposure. Ambient pressure XPS studies of water exposure to these surfaces suggest that high water pressures tend to passivate the surface, inhibiting extensive oxide formation. † These authors contributed equally to the work described here.
Lithiated graphite and lithium thin films have been used in fusion devices. In this environment, lithiated graphite will undergo oxidation by background gases. In order to gain insight into this oxidation process, thin (b 15 monolayer (ML)) lithium films on highly ordered pyrolytic graphite (HOPG) were exposed to O 2(g) and H 2 O (g) in an ultra-high vacuum chamber. High resolution electron energy loss spectroscopy (HREELS) was used to identify the surface species formed during O 2(g) and H 2 O (g) exposure. Auger electron spectroscopy (AES) was used to obtain the relative oxidation rates during O 2(g) and H 2 O (g) exposure. AES showed that as the lithium film thickness decreased from 15 to 5 to 1 ML, the oxidation rate decreased for both O 2(g) and H 2 O (g) . HREELS showed that a 15 ML lithium film was fully oxidized after 9.7 L (L) of O 2(g) exposure and Li 2 O was formed. HREELS also showed that during initial exposure (b0.5 L) H 2 O (g) , lithium hydride and lithium hydroxide were formed on the surface of a 15 ML lithium film. After 0.5 L of H 2 O (g) exposure, the H 2 O (g) began to physisorb, and after 15 L of H 2 O (g) exposure, the 15 ML lithium film was not fully oxidized.
Lithiated graphite and lithium thin films have been used in fusion devices. In this environment, lithiated graphite will undergo oxidation by background gases. In order to gain insight into this oxidation process, thin (< 15 monolayer (ML)) lithium films on highly ordered pyrolytic graphite (HOPG) were exposed to O 2(g) and H 2 O (g) in an ultra-high vacuum chamber. High resolution electron energy loss spectroscopy (HREELS) was used to identify the surface species formed during O 2(g) and H 2 O (g) exposure. Auger electron spectroscopy (AES) was used to obtain the relative oxidation rates during O 2(g) and H 2 O (g) exposure. AES showed that as the lithium film thickness decreased from 15 to 5 to 1 ML, the oxidation rate decreased for both O 2(g) and H 2 O (g). HREELS showed that a 15 ML lithium film was fully oxidized after 9.7 Langmuir (L) of O 2(g) exposure and Li 2 O was formed. HREELS also showed that during initial exposure (< 0.5 L) H 2 O (g) , lithium hydride and lithium hydroxide were formed on the surface of a 15 ML lithium film. After 0.5 L of H 2 O (g) exposure, the H 2 O (g) began to physisorb, and after 15 L of H 2 O (g) exposure, the 15 ML lithium film was not fully oxidized.
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