Inner-shell excitation spectroscopy of peroxides

Abstract

a b s t r a c t O 1s inner-shell excitation spectra of a number of vapor phase molecules containing peroxide bonds -hydrogen peroxide (H 2 O 2 ), di-t-butylperoxide ( t BuO t Bu), benzoyl peroxide, ((C 6 H 5 (CO)O) 2 ), luperox-F [1,3(4)-bis(tertbutylperoxyisopropyl) benzene], and analogous, non-peroxide compounds -water, t-butanol and benzoic acid have been measured. C 1s spectra are also reported. O 1s spectra of solid benzoic acid, di-t-butylperoxide and luperox-F recorded using a scanning transmission X-ray microscope, are also reported, and compared to the corresponding gaseous spectra. Spectral interpretation was aided by comparing the spectra of the peroxide and non-peroxide counterparts and with ab initio calculations. A characteristic O 1s ? r ⁄ O-O transition at 533.0(3) eV is identified in each peroxide species, which is absent in the corresponding non-peroxide counterpart species. The energy and intensity of the 533 eV peroxide feature is stable and thus useful for analysis of peroxides in mixtures, such as tracking residual peroxide initiators, or peroxides produced in fuel cells.

The Highest Oxidation State of Rhodium: Rhodium(VII) in [RhO3]+

“…[36,37] This s * resonance is an indication of the existence of an oxygen-oxygen bond, and is a characteristic spectroscopic fingerprint of chemisorbed or physisorbed dioxygen at metal surfaces in the peroxide or superoxide forms, [38,39] of solid-phase superoxides, [40,41] and of peroxide units in H 2 O 2 and organic compounds. [42,43] This suggests the presence of at least one dioxygen unit in RhO 4 ½ � þ , and thus confirms that tetraoxido rhodium is not formed. [25,27,28] Although the oxidation state of rhodium in RhO 4 ½ � þ cannot be unambiguously assigned from the oxygen K-edge alone, we tentatively assign the formal oxidation states of + 4 or + 5, see Supporting Information for details.…”

“…In contrast, the species shows a ‐like transition around 540 eV, similar to the transition of molecular oxygen [36, 37] . This resonance is an indication of the existence of an oxygen–oxygen bond, and is a characteristic spectroscopic fingerprint of chemisorbed or physisorbed dioxygen at metal surfaces in the peroxide or superoxide forms, [38, 39] of solid‐phase superoxides, [40, 41] and of peroxide units in and organic compounds [42, 43] . This suggests the presence of at least one dioxygen unit in , and thus confirms that tetraoxido rhodium is not formed [25, 27, 28] .…”

An Experimental Investigation of the Adsorption of a Phosphonic Acid on the Anatase TiO2(101) Surface

“…Note a small feature is present at 286.5 eV in all experimental data but not present in the StoBe-calculated spectra, we therefore assume that this is substrate related. A clear peak can be seen at 288.2 eV, which has been assigned to a mixture of Rydberg transitions and transitions to features of the C–H σ* bonds. − The small bump at higher photon energy, at 289.7 and 290.0 eV in the experimental and StoBe-calculated spectra, respectively, can only be seen in the C6 spectra and is therefore attributed to transitions C 1s C–P → σ* transitions. The reason for the difference in energy of the experimental and calculated spectra in this region is unclear.…”

Die höchste Oxidationsstufe von Rhodium: Rhodium(VII) in [RhO3]+

“…Diese ‐Resonanz zeigt das Vorhandensein einer Sauerstoff–Sauerstoffbindung an und ist ein charakteristisches Merkmal des als Peroxid oder Superoxid an Metalloberflächen chemi‐ oder physisorbierten Disauerstoffs, [38, 39] der Festkörpersuperoxide, [40, 41] oder des Peroxids in bzw. in organischen Verbindungen [42, 43] . Dies deutet auf die Anwesenheit mindestens eine Disauerstoffspezies in hin und bestätigt somit das Fehlen des Tetraoxidorhodiumkations [25, 27, 28] .…”

“…in organischen Verbindungen. [42,43] Dies deutet auf die Anwesenheit mindestens eine Disauerstoffspezies in RhO 4 ½ � þ hin und bestätigt somit das Fehlen des Tetraoxidorhodiumkations. [25,27,28] Die Oxidationsstufe von Rhodium in RhO 4 ½ � þ kann alleine über die Sauerstoff K-Kantenanregung zwar nicht eindeutig bestimmt werden, wir ordnen hier aber vorläufig eine formale Oxidationsstufe von + 4 oder + 5 zu, siehe Hintergrundinformationen für weitere Erläuterungen.…”