We have developed a mlcroanalytlcal Instrument to analyze the organk constltuonts of partlculates and Inhomogeneous samples wtth aspaUal ramlutbn ol approxlmatdy 40 pm. Om method, two-step laser desorptlon/laser lonlzatlon mass spectrometry (L2MS), uses an Infrared laser to volatlllze constttuent mokuks Intact and an ultraviolet l a w to lonlze desorbed molecules In a selective manner with Imle or no frcrqrwntcrtion. In partlcular, our lnrtrwnent Is currently tuned to detect polycycllc aromatic hydrocarbons (PAHs), whlch have a strong aboorptlon cross section at the lonlzatlon laser wavelength of 266 m. The detection lhnlt of our Instrmnt k approxbnately 6 hnol for the compound wonene (CUH,*). We demonstrate the use of thk Instrument to analyze acld reddues from SIX motrltw the samples cor#kt of particles that are about 200 pm In dlameter. Quantltatlve and qualltatlve trends In PAH comporltlon are IdentHled for different classes of metwrltes. SgnHIcant dMeronces are seen between the carbonaceous and ordlnary chondrftes. Moreover, wlthln a rlngk clam of ordlnary chondrltes we see an Increase h dkybtbn wtth Increasing petrographk type (thennal metamorphlsm).

The reaction I2M→hν I2(B,v′, j′)+M has been studied experimentally for excitation above the dissociation limit of the I2M B state. A surprisingly large amount of the available energy is found as relative translational energy of the I2 and M products. These results have been interpreted in terms of a one atom ‘‘cage effect,’’ where the iodine atoms are prevented from dissociating by the presence of the rare gas atom M. A purely kinematic cage effect could occur on a single electronically excited potential energy surface, namely the one correlating to the I2(B) state plus M in its electronic ground state. In this paper we discuss another possible mechanism for a pathway leading to bound I2, which involves an electronic nonadiabatic transition. Above the I2M(B) threshold the 1Π1u electronic state can also be excited. Since the 1Π1u and the B states can be coupled by the presence of the rare gas atom, there is a finite probability for an electronic transition from 1Π1u to B, with the energy difference being transformed into relative kinetic energy of the rare gas atom with respect to I2 after a fraction of the available energy has been used to break the van der Waals bond. The relationship between this mechanism and the electronic predissociation of I2M(B) van der Waals molecules at much lower energies, as well as the collision induced electronic predissociation of I2(B), are also mentioned. Finally the possibility of observing similar transitions in other halogen–rare gas clusters is considered.

The photodissociation of I2M van der Waals clusters is studied at several wavelengths above the B state dissociation limit with M = Ne, Ar, Kr, and Xe. The I2 product vibrational state distributions are obtained by measuring the dispersed B -» X fluorescence and analyzing the resulting spectra. Excitation above the B state dissociation limit leads to significantly different reaction dynamics compared to excitation of the bound levels of the B state studied previously. Among others the recoil energies of the I2 and M fragments are much larger, and the distributions of rovibrational states in the I2 product are much wider in the present experiments. The relative translational energy in the I2* and M photodissociation products is found to be significantly larger than predicted by recent quasi-classical trajectory calculations.

The selectivity of copper deposition from copper (II) bis-hexafluoroacetylacetonate on SiO2 patterned with a platinum seeding layer is studied as a function of the reagent gas mixture. On platinum, the copper film growth rate increases with the amount of water vapor in the gas flow, and is independent of the chemical nature of the carrier gas used (H2 or He). The selectivity of the copper deposition is significantly improved when using He rather than H2 as carrier gas, especially at high water vapor concentrations where rapid film growth can be obtained.

The deposition of copper by low pressure chemical vapor deposition (CVD) from copper bis-hexafluoroacetylacetonate is monitored in real time and in situ by the measurement of the optical reflectivity and electrical resistance of the growing metal film. Changes of the deposit morphology during growth were analyzed by interrupting the CVD process at different stages and observing the samples by transmission electron microscopy. Pure copper is deposited at a temperature of 400~ and 1 mbar total reactor pressure of helium, precursor, and water vapor. Two successive regimes are distinguished in the deposition: island formation and continuous film growth. The transition between these two regimes is visible in the real time specular reflectance measurement. The copper deposition rate is twice higher during the island growth than during the continuous film growth at the applied conditions. The influence of a metal seeding layer (from 0.001 monolayer to 1 monolayer) on the copper deposition is shown both in the real time measurements and in the ex situ analysis of films, ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 169.230.243.252 Downloaded on 2015-04-05 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 169.230.243.252 Downloaded on 2015-04-05 to IP