Luning Zhang

Matrix-isolation infrared spectroscopic studies on ablated products generated from laser ablation of Ta2O5 and Ta in ambient O2/Ar gas

Abstract Using matrix-isolation infrared spectroscopy, 532 nm pulsed laser ablation of Ta2O5 and Ta targets in O2/Ar gas ambient has been investigated. The major ablated products of the tantalum-containing oxides were found to be the neutrals TaO, TaO2, (O2)TaO2, and the anions TaO2−, TaO3−, as well as cations TaO+, TaO2+ in minority. The observed infrared absorptions of these tantalum-containing oxides were reproduced by DFT calculations of vibrational fundamentals. The formation reaction channels of these products during the laser ablation process have been discussed.

Reactions of titanium oxides with water molecules. A matrix isolation FTIR and density functional study

Reactions of titanium dioxides with water molecules have been studied by matrix isolation infrared and density functional theoretical calculations. In solid argon, titanium dioxide molecules reacted with water to form OTi(OH)2 molecules spontaneously on annealing. The potential energy surface along the TiO2+H2O→OTi(OH)2 reaction path was calculated. Although titanium dioxide–water complex was predicted to be stable, this complex was not observed due to low energy barrier and high exothermicity for the hydrolysis reaction. Evidence is also presented for the formation of OTi–OH2 complex.

Reactions of laser-ablated Y and La atoms with H2O Infrared spectra and density functional calculations of the HMO, HMOH and M(OH)2 molecules in solid argon

Abstract Reactions of laser-ablated Y and La atoms with water molecules have been studied using matrix-isolation FTIR spectroscopy and density functional calculations. The reaction products were identified based on isotope labeled experiments and density functional calculations. For both Y and La atom reactions with H 2 O, the major reaction products are the HMOH, MO and M(OH) 2 (M=Y and La) molecules. In addition, HMO and HM(OH) 2 were produced on matrix sample annealing or UV broadband photolysis. Evidence is also presented for the formation of the HYOH + species. The potential energy surfaces for the Y, La+H 2 O reactions have been calculated to interpret the reaction mechanisms.

Activation of CO2 by Zr atom. Matrix-isolation FTIR spectroscopy and density functional studies

Abstract Combined experimental and theoretical studies have been performed for examining the interaction between Zr atom and CO 2 . Matrix-isolation FTIR spectra reveal that OZrCO is the main reaction product of laser-ablated Zr with CO 2 , identified by IR bands at 1837.8 and 878.9 cm −1 , correlating to the C–O and Zr–O stretching modes, respectively. Density functional calculations at the B3LYP level have been used to characterize the formation channel of the insertion product OZrCO. We have found that interaction of ground state Zr atom (4d 2 5s 2 ) with CO 2 on the triplet energy surface leads eventually to the insertion product OZrCO and the process is barrierless, indicating that activation of CO 2 by Zr atom requires no energy input. The theoretical results are consistent with the experimental observations.

Formation and characterization of the AsCO and AsCO- molecules. A matrix isolation FTIR and theoretical study

Abstract Infrared spectra of arsenic carbonyls trapped in an argon matrix by co-condensation of laser-ablated arsenic atoms and electrons with carbon monoxide are reported. Based on isotopic substitution experiments and theoretical calculations, an IR band at 1919.3 cm −1 has been assigned to the C–O stretching vibration of the neutral AsCO, and a 1756.4 cm −1 band to the C–O stretching mode of the AsCO − anion. The ground states of AsCO and AsCO − were predicted to be 2 Π and 1 Σ + , respectively. The formation mechanism and the nature of bonding are discussed.

The AlCO− and Al(CO)2− anions: Matrix isolation infrared spectra and density functional theory studies

After deposition of laser ablated aluminum with CO in excess argon at 11 K, distinct IR bands at 1682.3, 1803.9, and 1741.0 cm−1 have been observed in addition to the absorptions of neutral AlCO and Al(CO)2. With the aid of 13CO isotope enriched experiments and density functional calculations, the band at 1682.3 cm−1 has been assigned to the C–O stretch vibration of the AlCO− anion. Absorptions at 1803.9 and 1741.0 cm−1 have been assigned to the symmetric and antisymmetric C–O stretching vibrations of the Al(CO)2− anion, respectively. Vertical detachment energies of AlCO− and Al(CO)2− as well as the electron affinities of AlCO and Al(CO)2 have been calculated. The properties of MCO− anions (M=B, Ga, and In) have also been predicted for comparison with those of AlCO−.

Mobility of oxygen atoms generated from photolysis of O3 isolated in argon matrices

The mobility of oxygen atoms generated from ultraviolet (UV) photolysis of O3 isolated in argon matrices is investigated both theoretically and experimentally. The simulations via molecular dynamics show that O(1D) atoms generated in single, double, and triple substitutional sites can migrate through the matrices by a distance about 1 nm within several picoseconds, but the photogenerated O(3P) atoms are confined to the original trapping sites. In order to examine the mobility of the O(1D) atoms experimentally, the probing molecules of CF3Br (or CF3I) are so highly diluted in the matrix of O3/Ar that the separations between the probing molecules and the precursor ozone molecules are sufficiently large, and the reaction products CF3OBr (or CF3OI) are observed after irradiation with a 266 nm laser. Based on an analysis of the reaction rates, it is shown that the products are only generated from the probing molecules reacting with the O(1D) but not O(3P) atoms, suggesting that matrices can serve as a “sieve” ...

Reaction of silicon dioxide with water: a matrix isolation infrared and density functional theoretical study

Abstract Reactions of silicon dioxide with water molecules have been studied by matrix isolation infrared and density functional theoretical calculations. Silicon dioxides were prepared by reactions of laser ablated silicon atoms with oxygen in excess argon. When water molecules were added in the reagent gas, silicic acid H 2 SiO 3 molecules were produced spontaneously on annealing. Isotopic substitution experiments showed that the H 2 SiO 3 molecules were formed by reactions of silicon dioxide with water. The potential energy surface for silicon dioxide and water reaction was calculated. Although silicon dioxide–water complex was predicted to be stable, this complex was not observed due to low energy barrier and high exothermicity for the hydrolysis reaction.

A theoretical study on the novel molecule OSiCO and its isomers

Abstract Various isomers with the constitution OSiCO are located with ab initio MP2 as well as B3LYP methods using 6-311G(d) basis sets. On the singlet potential surface, the van der Waals complex OSi⋯CO is calculated to be most stable. This molecule has a planar structure in which the SiO and CO subunits are arranged between a perpendicular and a parallel configuration. The bent Si–OCO complex and trans -OSiCO molecule are the most stable species on the triplet energy surface. A modified version of the G2/MP2 method has been used to obtain energies of high accuracy. The vibrational frequencies of all the isomers are predicted.

Structure and stability of LiOMn molecule generated by laser ablation

A new hetero metal oxide LiOMn was produced by 355 nm laser ablation of a LiMn2O4 target and identified via time-resolved quadrupole mass spectrometry. Theoretical calculations predicted that this molecule exhibits a highly ionic electronic structure with a linear geometry in which the lithium is attached onto the oxygen atom.