Threshold photoelectron spectroscopy of organosulfur radicals.

We report vibrationally resolved threshold photoelectron spectra of several sulfur-containing reactive intermediates. This includes the organosulfur radicals CHS, CHS, CHSH, CHS, and SH, which are relevant in atmospheric chemistry and in astrochemical settings. Due to the high reactivity, the radicals were prepared pyrolysis of (CH)S.

Experimental and theoretical investigation of the Auger electron spectra of isothiocyanic acid, HNCS.

We investigate isothiocyanic acid, HNCS, by resonant and nonresonant Auger electron spectroscopy at the K-edge of carbon and nitrogen, and the L-edge of sulfur, employing soft X-ray synchrotron radiation. The C1s and N1s ionization energies as well as the S2s and S2p ionization energies are determined and X-ray absorption spectra reveal the transitions from the core to the virtual orbitals. Final states for all normal Auger electron spectra and the resonant ones recorded at the carbon and nitrogen edge are assigned and rationalized with theoretical spectra obtained with a wave-function based protocol.

Photoelectron spectrum of the pyridyl radical.

We report the photoelectron spectrum of the pyridyl radical (CHN), a species of interest in astrochemistry and combustion. The radicals were produced hydrogen abstraction in a fluorine discharge and ionized with synchrotron radiation. Mass-selected slow photoelectron spectra of the products were obtained from photoelectron-photoion coincidence spectra.

X-ray induced fragmentation of fulminic acid, HCNO.

The fragmentation of fulminic acid, HCNO, after excitation and ionization of core electrons was investigated using Auger-electron-photoion coincidence spectroscopy. A considerable degree of site-selectivity is observed. Ionization of the carbon and oxygen 1s electron leads to around 70% CH+ + NO+, while ionization at the central N-atom produces only 37% CH+ + NO+, but preferentially forms O+ + HCN+ and O+ + CN+.

Photoelectron spectroscopy and dissociative photoionization of fulminic acid, HCNO.

We report a joint experimental and computational study of the photoelectron spectroscopy and the dissociative photoionization of fulminic acid, HCNO. The molecule is of interest to astrochemistry and astrobiology as a potential precursor of prebiotic molecules. Synchrotron radiation was used as the photon source.

Bonding in Low-Coordinated Organoarsenic and Organoantimony Compounds: A Threshold Photoelectron Spectroscopic Investigation.

Methyl and methylene compounds of arsenic and antimony have been studied by photoelectron photoion coincidence spectroscopy to investigate their relative stability. While for As both HAs=CH , As-CH and the methylene compound As=CH are identified in the spectrum, the only Sb compound observed is Sb-CH . Thus, there is a step in the main group 15 between As and Sb, regarding the relative stability of the methyl compounds.

Threshold photoelectron spectroscopy of trimethylborane and its pyrolysis products.

Trimethylborane (TMB) and its chemistry upon pyrolysis have been investigated by threshold photoelectron spectroscopy. TMB shows an unstructured spectrum and its adiabatic ionization energy (IE) has been determined to be 9.93 ± 0.

Auger electron spectroscopy of fulminic acid, HCNO: an experimental and theoretical study.

HCNO is a molecule of considerable astrochemical interest as a precursor to prebiotic molecules. It is synthesized by preparative pyrolysis and is unstable at room temperature. Here, we investigate its spectroscopy in the soft X-ray regime at the C 1s, N 1s and O 1s edges.

Ammonia Borane, NH BH : A Threshold Photoelectron-Photoion Coincidence Study of a Potential Hydrogen-Storage Material.

We have investigated the photoionization of ammonia borane (AB) and determined adiabatic ionization energy to be 9.26±0.03 eV for the X E←X A transition.

Photoelectron spectroscopy of low valent organophosphorus compounds, P-CH, H-PCH and PCH.

We report the mass-selected slow photoelectron spectra of three reactive organophosphorus species, PCH, and the two isomers, methylenephosphine or phosphaethylene, HPCH and methylphosphinidine, P-CH. All spectra were recorded by double imaging photoelectron-photoion coincidence spectroscopy (iPEPICO) using synchrotron radiation and all species were generated in a flow reactor by the reaction of trimethyl phosphine with fluorine atoms. Adiabatic ionisation energies of 8.

Threshold photoelectron spectroscopy of iminoborane, HBNH.

We report the mass-selected threshold photoelectron spectrum (ms-TPES) of iminoborane (HBNH), generated by pyrolysis of borazine. The adiabatic ionization energy (IE) of the XΠ ← X Σ transition was determined to be 11.31 ± 0.

Photoelectron Photoion Coincidence Spectroscopy of NCl and NCl.

We investigate NCl and the NCl radical by photoelectron-photoion coincidence spectroscopy using synchrotron radiation. The mass selected threshold photoelectron spectrum (ms-TPES) of NCl is broad and unstructured due to the large geometry change. An ionization energy of 9.

Threshold Photoelectron Spectrum of Cyclobutadiene: Comparison with Time-Dependent Wavepacket Simulations.

The CH isomer cyclobutadiene (CBD) is the prime model for antiaromaticity and thus a molecule of considerable interest in chemistry. Because it is highly reactive, it can only be studied under isolated conditions. Its electronic structure is characterized by a pseudo-Jahn-Teller effect in the neutral and a ⊗ β Jahn-Teller effect in the cation.

Fragmentation of isocyanic acid, HNCO, following core excitation and ionization.

We report a study on the fragmentation of core-ionized and core-excited isocyanic acid, HNCO, using Auger-electron/photoion coincidence spectroscopy. Site-selectivity is observed both for normal and resonant Auger electron decay. Oxygen 1s ionization leads to the CO + NH ion pairs, while nitrogen 1s ionization results in three-body dissociation and an efficient fragmentation of the H-N bond in the dication.

Femtosecond dynamics of diphenylpropynylidene in ethanol and dichloromethane.

Carbon chains with an odd number of C atoms are reactive intermediates with a high biradical character. Here we report a joint experimental and computational investigation of the dynamics of diphenylpropynylidene, CH-C-CH, in dichloromethane and ethanol. The biradical is generated by ultraviolet light from 1,3-diphenyldiazopropyne.

Kinetics of 1- and 2-methylallyl + O reaction, investigated by photoionisation using synchrotron radiation.

The reaction kinetics of the isomers of the methylallyl radical with molecular oxygen has been studied in a flow tube reactor at the vacuum ultraviolet (VUV) beamline of the Swiss Light Source storage ring. The radicals were generated by direct photodissociation of bromides or iodides at 213 nm. Experiments were conducted at room temperature and low pressures between 1 and 3 mbar using He as the buffer gas.

Decomposition of Picolyl Radicals at High Temperature: A Mass Selective Threshold Photoelectron Spectroscopy Study.

The reaction products of the picolyl radicals at high temperature were characterized by mass-selective threshold photoelectron spectroscopy in the gas phase. Aminomethylpyridines were pyrolyzed to initially produce picolyl radicals (m/z=92). At higher temperatures further thermal reaction products are generated in the pyrolysis reactor.

Metamorphic meta isomer: carbon dioxide and ketenes are formed via retro-Diels-Alder reactions in the decomposition of meta-benzenediol.

The deoxygenation reaction of m-benzenediol (resorcinol), an important lignin model compound, was studied in a hot microreactor. We revealed three decomposition channels by detecting elusive and reactive intermediates and product isomers selectively and found that resorcinol, similarly to catechol (o-benzenediol) and hydroquinone (p-benzenediol), (i) gets decarbonylated to yield hydroxycyclopentadiene. Additionally, (ii) decarboxylation (CO loss) yields CH species in a retro-Diels-Alder reaction from a lactone species.