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Your search keyword '"Ashfold, M.N.R."' showing total 228 results
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228 results on '"Ashfold, M.N.R."'

11. Application of a quantum cascade laser for time-resolved, in situ probing of CH4/H2 and C2H2/H2 gas mixtures during microwave plasma enhanced chemical vapor deposition of diamond

Author

Cheesman, A., Duxbury, G., Smith, J.A., Ashfold, M.N.R., Langford, N., and Wright, S.

Subjects
Quantum chemistry -- Research, Diamond crystals -- Electric properties, Diamonds -- Electric properties, Chemical reactions -- Research, Chemicals, plastics and rubber industries
Abstract

The utility of pulsed quantum cascade lasers for in situ probing of the chemistry in microwave plasma activated hydrocarbon/Ar/H2 gas mixtures used for diamond thin film growth is reported, while CH4 and C2H2 molecules are monitored along with their interconversion. The observed trends are rationalized qualitatively within the framework of previously reported models.

Published
2006

14. Measurements of C(sub 2) and CH concentrations and temperatures in a dc arc jet using cavity ring-down spectroscopy

Author

Wills, J.B., Smith, J.A., Boxford, W.E., Elks, J.M.F., Ashfold, M.N.R., and Orr-Wing, A.J.

Subjects
Spectrum analysis -- Usage, Carbon compounds -- Chemical properties, Plasma jets -- Usage, Physics
Abstract

The use of cavity ring-down spectroscopy (CRDS) to record spectra of C(sub 2)(a) and CH(X) radicals in a dc plasma jet reactor operating with an Ar/H(sub 2)/CH(sub 4) gas mixture is demonstrated. The results presented demonstrate the value of CRDS detection for quantitative determination of radical concentrations, even for a medium that is intensely luminous and strongly emitting on the lines monitored in absorption.

Published
2002

30. Measurement and modeling of Ar/[H.sub.2]/C[H.sub.4] arc jet discharge chemical vapor deposition reactors. I. Intercomparison of derived spatial variations of H atom, [C.sub.2], and CH radical densities

Author

Rennick, C.J., Henney, J.J., Wills, J.B., Ashfold, M.N.R., Orr-Ewing, A.J., and Mankelevich, Yu.A.

Subjects
Argon -- Chemical properties, Carbon -- Chemical properties, Cavity resonators -- Usage, Chemical vapor deposition -- Analysis, Physics
Abstract

The cavity ring-down spectroscopy (CDRS) absorption measurements of column densities with x-direction spatial resolution for H(n=2) atoms and [C.sub.2](a) and CH(X) radicals are described. A two dimensional computer model has captured the variation of the parameters with changes to operating conditions of the reactor such as flows of [H.sub.2] and C[H.sub.4] and input power.

Published
2007

31. Measurement and modeling of Ar/[H.sub.2]/C[H.sub.4] arc jet discharge chemical vapor deposition reactors II: modeling of the spatial dependence of expanded plasma parameters and species number densities

Author

Mankelevich, Yu. A., Ashfold, M.N.R., and Orr-Ewing, A.J.

Subjects
Argon -- Chemical properties, Argon -- Electric properties, Chemical vapor deposition -- Analysis, Diffusion -- Analysis, Electric discharges -- Analysis, Electric discharges through gases -- Analysis, Physics
Abstract

A two-dimensional computer model applicable to dc arc jet reactors operating on argon/hydrogen/hydrocarbon gas mixtures and is used for chemical vapor deposition of micro- and nanocrystalline diamond and diamondlike carbon films is described. The modifications to the boundary conditions and model reactor geometry show that it can be used at a lower power arc jet reactor.

Published
2007

32. Resonance enhanced multiphoton ionisation spectroscopy of carbonyl sulphide

Author

Morgan, R.A., Baldwin, M.A., Orr-Ewing, A.J., Ascenzi, D., Ashfold, M.N.R., Buma, W.J., Scheper, C.R., de Lange, C.A., and HIMS former research (FNWI)

Subjects
Resonance-enhanced multiphoton ionization, Chemistry, General Physics and Astronomy, Resonance, Quantum defect, symbols.namesake, Ionization, Excited state, Rydberg atom, Rydberg formula, symbols, Physical and Theoretical Chemistry, Atomic physics, Spectroscopy
Abstract

Rydberg excited states of the OCS molecule in the energy range 70500–86000 cm−1 have been investigated via the two and three photon resonance enhancements they provide in the mass resolved multiphoton ionization (MPI) spectrum of a jet‐cooled sample of the parent molecule. Spectral interpretation has been assisted by companion measurements of the kinetic energies of the photoelectrons that accompany the various MPI resonances. The present study supports the earlier conclusions of Weinkauf and Boesl [J. Chem. Phys. 98, 4459 (1993)] regarding five Rydberg origins in the 70500–73000 cm−1 energy range, attributable to, respectively, states of 3Π, 1Π, 3Δ, 1Δ and 1Σ+ symmetry arising from the 4pλ←3π orbital promotion. We also identify a further 21 Rydberg origins at higher energies. These partition into clumps with quantum defects ca. 3.5 and 4.5, which we associate with the orbital promotions npλ←3π (n=5,6), and others with near integer quantum defect which are interpretable in terms of excitation to s,d and (...

Published
1996

33. Observation of the SCI radical by resonance enhanced multiphoton ionisation spectroscopy

Author

Howe, J.D., Ashfold, M.N.R., Morgan, R.A., Wester, D.A., Western, C.M., Buma, W.J., Milan, J.B., de Lange, C.A., and HIMS former research (FNWI)

Subjects
Excitation wavelength, Chemistry, Ionization, Transition dipole moment, Resonance, Physical and Theoretical Chemistry, Rydberg state, Atomic physics, Spectroscopy, Symmetry (physics)
Abstract

Three hitherto unobserved vibrational levels of the b′3Σ–u electronic state of P2 have been identified via the rotationally resolved, one-photon resonance enthancements they provide in the multiphoton ionisation spectrum of this radical. Analysis yields an extended set of spectroscopic constants for the b′3Σ–u state and a first estimate of the relative strengths of the parallel and perpendicular contributions to the P2(b′3Σ–u–X 1Σ+g) transition moment. One additional, particularly intense but unresolved feature observed at an excitation wavelength of ca. 320.75 nm is tentatively assigned in terms of a two-photon resonance involving a Rydberg state of P2 with 1Σ+g symmetry.

Published
1995

34. The Science Case for 4GLS

Author

Allan, R.J., Allen, M.P., Alexandrov, A.S., Ashfold, M.N.R., Atkinson, R., Avaldi, L., Bain, C.D., Bancroft, J., Barrett, S.D., Barron, L.D., Bayliss, S., Becker, U., Benning, L.G., Berrah, N., Binns, C., Bisby, R.H., Bizau, J.M., Blake, R.J., Bowler, M.A., Bowyer, J., Brettle, J., Briggs, D., Brown, L.M., Brown, W.A., Burke, P.G., Cacho, C., Carter, R., Catlow, R., Cernik, R.J., Chesters, M., Clark, S.A., Clarke, D.T., Clarke, J.A., Codling, K., Cogdell, R., Connaughton, D., Connerade, J.P., Costello, J.T., Crapper, M.D., Creaser, C., Currell, F.J., Davies, P.B., de Jong, M., Dessent, C., Dhanak, V.R., Dobson, D.M., Dobson, P.J., Doig, A.J., Donovan, R.J., Dumas, P., Dunn, K., Dutuit, O., Dyke, J.M., Eastham, D.A., Egdell, R.G., Eland, J.H.D., Emerson, D.R., Eriksson, M., Erman, P., Evans, A., Evans, H., Evans, S., Field, T., Fielding, H., Fisher, A., Flavell, W.R., Ford, R., Frasinski, L.J., Freeman, N., Galayda, J.N., Gardner, P., Garside, J., Gay, N.J., Gejo, T., George, M., Gray, M.D., Greenshaw, T.J., Greig, D., Halsall, M.P., Hamilton, B., Harrison, N.M., Hasnain, S.S., Hatherly, P.A., Heathcote, P., Helliwell, J.R., Henderson, C.M.B, Hepburn, J., Hill, J., Hirst, G., Hirst, J.D., Holland, D.M.P., Horn, A.B., Horton, P., Hunt, M.R.C., Hutchinson, H., Inglesfield, J.E., Ivanov, V.K., Johnson, C.A.F., Johnson, L.N., Jones, D., Jones, F.H., Jones, G.R., Jones, L., Kadodwala, M., Karlsson, L., Kennedy, E.T., King, G.C., King, M.R.F., Kirkman, I.W., Kleese, K., Knight, P.L., Kylstra, N., Larkins, F.P., Latimer, C., Lawley, K.P., Leggett, G.J., Lewis, R.A., Lindsey, K., Lu, J.R., Lyng, F.M., Macdonald, M.A., Malins, A., Marangos, J.P., Margaritondo, G., Marsi, M., Marston, G., Martin, S.R., Martin-Fernandez, M.L., Mason, N.J., Matthew, J.A.D., McCoustra, M.R.S., McGilp, J., McGovern, I.T., McGrath, R., Meldrum, R.A., Meyer, M., Millar, T.J., Mitchell, D., Møller, S.P., Molster, F.J., Moriarty, P., Morin, P., Munro, I.H., Murdin, B.N., Nahon, L., Newell, W.R., Noble, C.J., Nordgren, E.J., Norman, P.R., O'Brien, P., O'Neill, P., O'Shea, P., Owen, H., Pain, R., Papiz, M., Parker, A., Parker, J., Parr, A., Pattrick, R., Pemble, M.E., Picardo, M., Pidgeon, C.R., Pinheiro, T.J.T., Poliakoff, E.D., Poole, M.W., Potts, A., Potvliege, R., Powis, I., Price, S.D., Quinn, F.M., Radford, S., Rachlew-Källne, E., Raval, R., Read, F.H., Reddish, T.J., Ridley, P.A., Roberts, G., Russell, A.E., Ryan, A.J., Sapelkin, A., Sato, S., Schneider, A., Seddon, E.A., Shaw, E.A., Shen, T., Sherwood, P., Šiller, L., Smith, A.D., Smith, D.A., Smith, I., Smith, S.L., Snowdon, K., Softley, T.P., Sokell, E., Southworth, S.H., Srivistava, G.P., Stankiewicz, M., Sule-Suso, J., Sutherland, J.C., Surman, M., Svensson, S., Taylor, A.O., Temmerman, W.M., Thomas, A., Tiddy, G.J., Tobin, M., Towns-Andrews, Elizabeth, Towrie, M., Truscott, G., Tuckett, R.P., Turner, Tracy, Twigg, M.V., Vagdama, P., van der Hart, H.W., Volk, M., Vrakkring, M.J.J., Walker, I.C., Wander, A., Wasserman, S.P., Watanabe, M., Weightman, P., Welton, T., West, J.B., Wharton, C.W., Whitehead, J.C., Williams, G.P., Winick, H., Withnall, R., Woodruff, D.P., and Zayats, A.

Subjects
Q1
Published
2001

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