This manuscript reports the potential-dependent adsorption and deposition of cisplatin on polycrystalline gold electrode. It was found that this process is mediated by the adsorption of phosphate... Show moreThis manuscript reports the potential-dependent adsorption and deposition of cisplatin on polycrystalline gold electrode. It was found that this process is mediated by the adsorption of phosphate anions on the gold electrode and that the maximum coverage of Pt adsorbed is given by the maximum coverage of phosphate adsorbed at a given potential. The interaction of cisplatin with the phosphate groups was confirmed by in situ FTIR spectroscopy under external reflexion configuration. Quantitative analysis suggests that the stoichiometry of the phosphate species and the cisplatin adsorbed was 1:1. Moreover, the relationship between the charge of the Pt deposited and the charge of the electrochemical surface area of the Pt deposited on the gold electrodes indicates that 3D nanoclusters of a few atoms of Pt were formed over the gold electrode upon the electrochemical reduction of the adsorbed cisplatin.The Pt nanoclusters formed under these conditions were later evaluated for the oxidation of a monolayer of carbon monoxide. The Pt nanoclusters showed a high overpotential for the oxidation of the carbon monoxide monolayer and the high oxidation overpotential was attributed to the absence of adsorption sites for OH species on the Pt clusters: only at potentials where the OH species are adsorbed at the edge between the Pt nanocluster and the gold support, the oxidation of the carbon monoxide on the Pt nanoparticles takes place. Show less
Kas, R.; Kortlever, R.; Yilmaz, H.; Koper, M.T.M.; Mul, G. 2015
Measurements were carried out on the CO J = 3-2 emission line at 345 GHz from a number of translucent and high-latitude molecular clouds, as well as on the J = 2-1 and J = 1-0 lines of both the (C... Show moreMeasurements were carried out on the CO J = 3-2 emission line at 345 GHz from a number of translucent and high-latitude molecular clouds, as well as on the J = 2-1 and J = 1-0 lines of both the (C-12)O and (C-13)O. It is shown that the physical conditions in the high-latitude clouds are very similar to those in the translucent clouds. The densities derived from measured (C-12)O 1-0/3-2 ratios were often found to be higher than those based on the C2 excitation, while densities derived from measured 3-2/(C-13)O 1-0 ratios were similar to those based on C2. Show less
Interstellar absorption-line spectroscopy of NGC 2264 is reported which shows that the CO molecule has a column density of 5 x 10 to the 18th/sq cm and a rotational excitation temperature of 28 K.... Show moreInterstellar absorption-line spectroscopy of NGC 2264 is reported which shows that the CO molecule has a column density of 5 x 10 to the 18th/sq cm and a rotational excitation temperature of 28 K. A direct upper limit on the H2 column density implies that at least 6 percent of a solar carbon abundance is in the form of CO. The upper limit on the H3(+) abundance implies that the cosmic-ray ionization rate is of the order of 10 to the -16th/s or less. The H3(+) upper limit, together with a previous radio detection of H2D(+) emission, implies either an enormous overabundance of the deuterated molecule or else that most of the radio emission comes from clouds not located directly between use and the infrared source. Observations of the sources AFGL 2591 and NGC 2024 IRS2 indicate that upper limits on H3(+) imply cosmic ray ionization rates of less than 3 and 60 x 10 to the -17th/s, respectively. Show less
Emission and absorption lines of H2 and CO in nuclei of several galaxies with strong NIR emission, including Centaurus A (NGC 5128), were studied at the La Silla observatory to obtain constraints... Show moreEmission and absorption lines of H2 and CO in nuclei of several galaxies with strong NIR emission, including Centaurus A (NGC 5128), were studied at the La Silla observatory to obtain constraints on the physical parameters of molecular material close to the nucleus of the NGC 5128 galaxy. Results show that, besides the (C-12)O, and (C-13)O emission and absorption lines toward the nucleus of NGC 5128, an unresolved source of excited H2 emission (of a size smaller than 95 pc) exists that appears to be collisionally excited. The new observations, combined with literature data, suggest that the nucleus of Cen A is surrounded by a disk of mass 2 x 10 to the 7th solar masses. It is shown that a circumnuclear disk with the outer edge at r - 160 pc, a thickness of 80 pc, a cavity with a radius of 40 pc, and a density distribution of about 1/sq r is consistent with all existing observations. Show less
Interstellar absorption lines of CH and CH(+) have been detected toward the star HD 210121, which is located behind a previously unknown high-latitude cloud. The CH observations and the measured... Show moreInterstellar absorption lines of CH and CH(+) have been detected toward the star HD 210121, which is located behind a previously unknown high-latitude cloud. The CH observations and the measured extinction toward the star provide independent measures of the H2 column density along the line of sight, which are compared with that deduced from CO mm observations. The inferred CH(+) column density is comparatively small, suggesting that shocks do not play a dominant role in the chemistry in the cloud. Show less
Recent work on the vacuum UV absorption spectrum of CO to the description of the photodissociation of interstellar CO and its principal isotopic varieties is discussed. The effects of line... Show moreRecent work on the vacuum UV absorption spectrum of CO to the description of the photodissociation of interstellar CO and its principal isotopic varieties is discussed. The effects of line broadening, self-shielding, shielding by H and H2, and isotope-selective shielding are examined as functions of depth into interstellar clouds. The photodissociation rates of the isotopic species are larger than that of (C-12)O inside the clouds by up to one to two orders of magnitude. A simple approximation to the attenuation by line absorption is given in tabular form. Computed abundances of CO and related species C and C+ are presented for a variety of interstellar clouds ranging from diffuse clouds to dense photodissociation regions. Several series of models of translucent clouds are presented which illustrate how the CO abundance increases rapidly with total cloud thickness. The variations of the isotopic abundances with depth and their sensitivity to temperature and total cloud thickness are explored in detail. Show less
Jannuzi, B.T.; Black, J.H.; Lada, C.J.; Dishoeck, E.F. van 1988
Optical absorption line observations of the B1 supergiant HD 169454 reveal the presence of an intervening translucent interstellar cloud. Millimeter wavelength observations of CO emission show that... Show moreOptical absorption line observations of the B1 supergiant HD 169454 reveal the presence of an intervening translucent interstellar cloud. Millimeter wavelength observations of CO emission show that the absorption lines can be attributed to a well-defined cloud approximately 18 by 22 min in extent at the same radial velocity as the C2 and CN absorption lines. The map of the CO emission shows three large condensations and evidence of unresolved structure on smaller scales. Various procedures for determining the cloud mass are compared. The estimated mass is 7-14 M solar masses if the cloud lies at the distance (D about 125 pc) of an extended atomic cloud at the same radial velocity, and is 250-500 M solar masses if the kinematic distance (D about 750 pc) is adopted. The dynamical state of the cloud is examined. The composition and structure of the cloud are discussed with reference to detailed theoretical models and the properties of other interstellar clouds. Show less
