Spectroscopy and Photoreactions of Organometallic Molecules on Surfaces

Chen, C. J.; Osgood, Richard M.

doi:10.1557/proc-17-169

Cited by 10 publications

(4 citation statements)

References 6 publications

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“…If the substrate primarily stabilizes the ground state, the energy difference increases causing the spectrum to blue shift. Chen and Osgood also observed a red shift of the absorbance spectrum upon adsorption of Cd(CH 3 ) 2 on fused silica. They also noted broadening and dampening of the vibrational components of the spectrum.…”

Section: Introductionmentioning

confidence: 85%

“…Chen and Osgood observed red shifts of the absorption spectrum for physisorbed Cd(CH 3 ) 2 molecules on fused silica at 0 °C, and pressures between 1 and 4 Torr. The degree of red shift was not quantified by the authors, but inspection of the published spectra indicates the shift was between 1 and 2 nm and reportedly increased with pressure.…”

Section: Discussionmentioning

confidence: 99%

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Ammonia Photodissociation Promoted by Si(100)

Finstad

Muscat

2014

J. Phys. Chem. A

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Using in situ X-ray photoelectron spectroscopy measurements after reaction, we show that hydrogen-terminated Si(100) perturbs the bonding of physisorbed NH3 enabling a photochemical decomposition pathway at wavelengths different from those characteristic of either the molecule in the gas phase or the semiconductor bandgap. UV illumination only of gas phase NH3 at partial pressures from 0.1 to 100 Torr produced a maximum at 10 Torr in the N surface coverage. This is in good agreement with a model of the radical production rate showing that at this pressure the gas density balances the flux of photons at the surface with energies sufficient to dissociate NH3. UV illumination of both the gas phase and the surface produced a monotonic increase in the N coverage with pressure as well as coverages that were 3-10 times higher than when only the gas phase was illuminated. The amine saturation coverage scaled with the UV fluence at 10 Torr and 75 °C, reaching 6.9 × 10(14) atoms/cm(2) (∼1 N atom per Si surface atom) at 19 mW/cm(2) and 12 × 10(14) atoms/cm(2) (∼1.8 N per Si) at 35 mW/cm(2). Monochromatic illumination showed that the wavelengths driving deposition were not correlated with the Si bandgap, but instead were roughly the same as gas phase photodissociation (λ < 220 nm). The primary driving force to replace the hydrogen termination with amine groups was direct photodissociation of NH3 molecules whose electronic structure was perturbed by interaction with the surface. Amine groups enhanced the surface reaction of water present as a contaminant in the source gas. These results show that molecules in weakly bound surface states can have a dramatic impact on the photochemistry.

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Section: Introductionmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Ammonia Photodissociation Promoted by Si(100)

Finstad

Muscat

2014

J. Phys. Chem. A

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“…TMG), where the absorption of one photon by the metal-trimethyl precursor will efficiently generate free metal atoms or metal-monomethyl fragments, whereas one photon absorbed by the metal-triethyl (or other ligands with /%hydrogen) precursor will induce free metal atoms or metal-hydride fragments. Further, a weak one-photon absorption at 220-260 nm (Fig.4) can still efficiently generate free metal atoms, which might result from a rib-ronically allowed quadrupole transition to a totally dissociative potential surface [16], and abundant metal-hydride fragments if the precursor molecule has fl-hydrogen [6], but only few metal-monomethyl radicals.…”

Section: Discussionmentioning

confidence: 99%

UV laser photofragment GaCH3 detected by far UV laser mass spectrometry

1989

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“…Though quite thin, such adsorbed layers often absorb ultraviolet (UV) radiation much more strongly than an equivalent number of molecules in the gas phase [4]. Photodissociation of adsorbed molecules occurs in much the same way as it does in the gas phase.…”

Section: Adsorbed Phase Reactionsmentioning

confidence: 99%