The effect of immersion time on the ordering properties of self-assembled docosanethiolate (C22) monolayers has been studied by reflection/absorption infrared spectroscopy (RAIRS). Starting with a chemically cleaned polycrystalline gold surface, we have found that an immersion time of 45 s in micromolar thiol solutions is sufficient to produce ordered “monolayer” films. These films have RAIR spectral features (peak position, line width, and integrated intensity) similar to those obtained with much longer immersion times. Decreasing the immersion time below 45 s gradually increases the disorder. The temperature dependence of the CH2 antisymmetric stretching (d-) peak position of thiol films obtained with an immersion time of 120 s is identical to ones obtained with very long immersion time (0.5 h to several days). In contrast, films obtained with a 5 s immersion time disorder at a lower temperature. Apart from immersion time and temperature, a large solvent effect has been observed based on real-time RAIRS measurements of the continuing film ordering during aging in vacuum. Finally, a new assignment of the shoulder appearing around 2931 cm-1 is proposed. We present arguments suggesting that the generally accepted Fermi resonance assignment of this shoulder should be modified to include a contribution from another vibrational mode.

/npsi/ctrl?action=rtdoc&an=8894813&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=8894813&lang=frAccess and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. Langmuir, 14, pp. 6579-6587, 1998 Characterization of self-assembled bilayers: silver-alkanethiolates Bensebaa, Farid; Ellis, T.; Kruus, E.; Voicu, R.; Zhou, Y.

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Enhancement of chargetransfer reaction rate constants by vibrational excitation at kinetic energies below 1 eV J. Chem. Phys. 79, 265 (1983); 10.1063/1.445566Rotational and vibrational energy distributions of 16OH(X 2Π) and 18OH(X 2Π) produced in the reaction of O(1 D) with H2O and H2 18OThe initial vibrational distributions in both energetically accessible channels of the reaction between O( ID) atoms and HCl molecules are reported. The measurements were made using very fast time-resolved Fourier transform spectroscopy to observe the emission spectra of the products before their vibrational populations could be altered by collisional relaxation. Both the OH from the reaction and the HCl created in the E-V energy transfer process have strongly inverted vibrational distributions. The cross section of the former is found to be about 20 times larger than that of the latter. Although spin forbidden, the E-V process is fast, due to the fact that the IA " and 3 A " surfaces of the HOCI intermediate are nearly energetically degenerate over a large region of configuration space. The results suggest that the dynamics of the interaction are dominated by the relatively slow O-Cl collision. The rapid motion of the H atom, in response to changes in the potential created by the motion of the heavier atoms, permits the system to sample the singlet-triplet intersection many times during the collision. OH rotational deactivation is very fast in this system; the average probability for rotational energy transfer in the v' = 3 level is more than four times larger than the gas kinetic collision probability. The time evolution of both vibrational distributions is also reported, and fast v-v energy transfer from vibrationally excited OH to ground state HCI is observed.