No abstract

A simple vibrational curvilinear internal coordinate Hamiltonian for bent H2X molecules is constracted by expanding the g matrix elements and the potential energy function in terms of the Morse variable y=1−exp(−ar) and retaining important local mode and Fermi resonance terms. The eigenvalues of this Hamiltonian are calculated variationally using Morse oscillator basis functions for the stretches and harmonic oscillator basis functions for the bend. The nonlinear least-squares method is used to optimize the potential energy parameters. The model is applied to water, hydrogen sulfide, and hydrogen selenide. Experimental vibrational levels up to 18 500 cm−1 for five symmetrical isotopic species of water are reproduced with a standard deviation of about 4 cm−1. For both hydrogen sulfide and hydrogen selenide two symmetrical isotopic species were included in the optimization procedure and standard deviations of 1.0 and 0.66 cm−1 were obtained. The potential energy parameters obtained agree well with previous anharmonic force field calculations.

Early stages of carbon monolayer nucleation on the copper (111) surface are systematically studied using densityfunctional theory calculations in the context of chemical vapor deposition and irradiation-mediated growth of graphene. By analyzing the kinetics of carbon atoms during their agglomeration, including surface, subsurface, and surface-to-bulk migration as well as dimer formation and diffusion, we draw a qualitative picture of the first stages of graphene growth on copper. The formation and migration of dimers and graphitic fragments happens at a much faster rate than the other competing processes, such as carbon migration into copper bulk and the dissociation of dimers into carbon monomers. To explain this tendency, which is an important factor in making copper such an effective graphene catalyst, we analyze in detail the electronic structure of dimers on surfaces and suggest that dimer stabilization and mobility stem from a delicate interplay between the carbon dimer σ p bonding orbitals and copper d and s electrons. Our results emphasize the role of mobile carbon dimer intermediates during the growth of graphene on Cu, Ag, and Au surfaces by chemical vapor deposition and irradiation-mediated methods, in which carbon atoms are implanted into copper foils beyond the solubility limit.

PostprintThis is the accepted version of a paper published in Journal of Breath Research. This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination.Citation for the original published paper (version of record):Schmidt, F., Vaittinen, O., Metsälä, M., Lehto, M., Forsblom, C. et al. (2013) Ammonia in breath and emitted from skin. Abstract. Ammonia concentrations in exhaled breath (eNH 3 ) and skin gas of 20 healthy subjects were measured on-line with a commercial cavity ring-down spectrometer and compared to saliva pH and plasma ammonium ion (NH + 4 ), urea and creatinine concentrations. Special attention was given to mouth, nose and skin sampling procedures and the accurate quantification of ammonia in humid gas samples. The obtained median concentrations were 688 parts per billion by volume (ppbv) for mouth-eNH 3 , 34 ppbv for nose-eNH 3 , and 21 ppbv for both mouth-and nose-eNH 3 after an acidic mouth wash (MW). The median ammonia emission rate from the lower forearm was 0.3 ng cm −2 minute −1 . Statistically significant (p<0.05) correlations between the breath, skin and plasma ammonia/ammonium concentrations were not found. However, mouth-eNH 3 strongly (p<0.001) correlated with saliva pH. This dependence was also observed in detailed measurements of the diurnal variation and the response of eNH 3 to the acidic MW. It is concluded that eNH 3 as such does not reflect plasma but saliva and airway mucus NH + 4 concentrations and is affected by saliva and airway mucus pH. After normalization with saliva pH using the HendersonHasselbalch equation, mouth-eNH 3 correlated with plasma NH + 4 , which points to saliva and plasma NH + 4 being linked via hydrolysis of salivary urea. Journal of Breath

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