Production and Reactivity of Ionized Clusters in the Gas Phase

A brief review of the experimental methods to obtain gas phase cluster ions is reported. Supersonic expansion and ionization, high pressure ion production and clusterization, ablation from solids are techniques used to study cluster chemistry. Studies of cluster ion formation from metal, metal oxides and metal carbides are illustrated together with considerations on their structure and stability

Photoexcitation in thin films deposited on silicon substrates by reactive pulsed laser ablation

Reactive pulsed laser ablation is a very interesting method to deposit thin films of several materials and compounds such as oxides, nitrides, semiconductors and superconductors. This technique relies on photoablation of pure elements, or a mixture of materials, with simultaneous exposure to a reactive atmosphere. In the case of oxides, reactions between the laser vaporized metals and oxygen lead to the formation of intermediate complexes and finally to oxide thin films. The reactivity of the plume has been already studied by our group in other oxides and nitrides productions and ascertained by Time of Flight Mass Spectrometry measurements [1].Thin films of semiconducting oxides such asIn2O3,SnO2, and multilayers of these two compounds have been deposited by Reactive Pulsed Laser Ablation, with the aim to evaluate the behaviour of such films under variable halogen lamp illumination.Deposition of these thin films has been carried out by a frequency doubled Nd-YAG laser (wavelength = 532 nm) on Silicon (100) substrates. A comparison, among indium oxide, tin oxide, and multilayers of indium and tin oxides, has been performed. The influence of physical parameters, such as substrate temperature and oxygen pressure in the deposition chamber, has been investigated. The deposited films have been characterized by Electric Resistance measurements

Photochemical R2PI study of chirality and intermolecular forces in supersonic beam

One and two-color, mass selected R2PI spectra of theS1←S0transitions in the bare(+)-(R)- 1-phenyl-1-ethanol(ER) and its complexes with different solvent molecules (solv) (-)-(R)-2-butanol(BR) or(+)-(S)-2-butanol(BS), (—)-(R)-2-pentanol (TR) or(+)-(S)-2-pentanol(TS) and(-)-(R)-2-butylamine(AR) or(+)-(S)-2-butylamine(AS), have been recorded after a supersonic molecular beam expansion. The one-color R2PI excitation spectra of the diastereomeric complexes are characterized by significant shifts of their band origin relative to that of bareER. The extent and the direction of these spectral shifts are found to depend upon the structure and the configuration ofsolvand are attributed to different short-range interactions in the ground and excited states of the complexes. In analogy with other diastereomeric complexes, the phenomenological binding energy of the homochiral cluster is found to be greater than that of the heterochiral one. Preliminary measurements of excitation spectrum of(+)-(R)-1-Indanol(IR) is also reported

Laser production of gas phase complexes of metal α-aminophosphonic acid mixtures and their role in chiral recognition

Clusters between first-group metal ions and chiralα-aminophosphonic acids have been readily generated by Pulsed Laser Ablation (PLA) and by Electrospray Ionization (ESI) and their fragmentation investigated by mass spectrometry. The complexes studied have the general formula[Me(I)Cl2]+, where Me(I) is H, Li, Na, or K, C is (R)-(—)-(1-aminoethyl) phosphonic acid(ER)and (S)-(+)-(1-aminoethyl) phosphonic acid(ES),(1R)-(+)-(1-amino-2-methylpropyl) phosphonic acid(PR)and (1S)-(—)-(1-amino-2-methylpropyl) phosphonic acid(PS),(1R)-(-)-(1-amino-hexyl) phosphonic acid (HR) and (1S)-(+)-(1-amino-hexyl) phosphonic acid (HS), o-phospho-L-serine (SS)ando-phospho-D-serine(SR), and L is a referenceα-aminophosphonic acid (E, P, H or S) of defined configuration. Collision induced dissociation (CID) of diastereomeric[Me(I)Cl2]+complexes leads to fragmentation patterns characterized by[Me(I)Cl]+/[Me(I)L2]+abundance ratios which depend upon the configuration of solute C. These different spectral features were correlated to the different stability of the diastereomeric[Me(I)CRL]+and[Me(I)CSL]+complexes in the gas phase