Dissociative Photoionization of Methyl Thiochloroformate, ClC(O)SCH3, following Sulfur 2p, Chlorine 2p, Carbon 1s and Oxygen 1s Excitations

The electronic transitions and the dissociativeionic photoionization mechanisms of gaseous ClC(O)SCH3have been investigated at the VUV and soft X-ray energyregions of S 2p, Cl 2p, C 1s, and O 1s core edges using tunablesynchrotron radiation and time-of-flight mass spectrometry.The relative abundances of the ionic fragments were obtainedfrom both PEPICO (photoelectron photoion coincidence)and PEPIPICO (photoelectron photoion photoion coincidence)spectra. The presence of a moderate site- and element-specific fragmentation effects and its implication regardingchemical reactions were analyzed. The relationship of the current results with the interstellar chemistry is also a goal of this pieceof work.Fil: Geronés, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Erben, Mauricio Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Romano, Rosana Mariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Cavasso Filho, Reinaldo L.. Universidade Federal do ABC; BrasilFil: Della Védova, Carlos O.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; Argentin

Calcium magneto-optical trap loaded from a decelerated atomic beam

FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOWe describe a new system for laser cooling and trapping of neutral Calcium atoms employing the ¹S0 -¹ P1 resonant transition at 423 nm. An on-axis magneto-optical trap (MOT) is loaded from a Zeeman decelerated atomic beam. When a single laser is used, in order to avoid perturbation of the trap by the deceleration laser beam, this one has been tightly focused near the MOT center, with a waist size much smaller than the atomic cloud. In order to test the efficiency of this novel technique, we have then employed a second, independent decelerating laser, with a profile mode matched to the atomic beam. For an oven temperature of 580±C this system can load 1.2 (2) x 10(7) atoms in 16 (1) ms. By the spatial extension of the atomic cloud the one dimension rms velocity was estimated to be 136 (12) cm/s, corresponding to a temperature of 9 (2) mK. The variation of the number of trapped atoms as a function of laser detuning and intensity, trap magnetic field gradient and oven temperature is analyzed. Spatial structures of the trapped atoms, like stable rings created by vortex forces, have been observed. This is the first time that these structures, already observed in alkali-metal elements, are reported in MOTs of alkaline-earth elements.We describe a new system for laser cooling and trapping of neutral Calcium atoms employing the ¹S0 -¹ P1 resonant transition at 423 nm. An on-axis magneto-optical trap (MOT) is loaded from a Zeeman decelerated atomic beam. When a single laser is used, in order to avoid perturbation of the trap by the deceleration laser beam, this one has been tightly focused near the MOT center, with a waist size much smaller than the atomic cloud. In order to test the efficiency of this novel technique, we have then employed a second, independent decelerating laser, with a profile mode matched to the atomic beam. For an oven temperature of 580±C this system can load 1.2 (2) x 10(7) atoms in 16 (1) ms. By the spatial extension of the atomic cloud the one dimension rms velocity was estimated to be 136 (12) cm/s, corresponding to a temperature of 9 (2) mK. The variation of the number of trapped atoms as a function of laser detuning and intensity, trap magnetic field gradient and oven temperature is analyzed. Spatial structures of the trapped atoms, like stable rings created by vortex forces, have been observed. This is the first time that these structures, already observed in alkali-metal elements, are reported in MOTs of alkaline-earth elements.We describe a new system for laser cooling and trapping of neutral Calcium atoms employing the ¹S0 -¹ P1 resonant transition at 423 nm. An on-axis magneto-optical trap (MOT) is loaded from a Zeeman decelerated atomic beam. When a single laser is used, in order to avoid perturbation of the trap by the deceleration laser beam, this one has been tightly focused near the MOT center, with a waist size much smaller than the atomic cloud. In order to test the efficiency of this novel technique, we have then employed a second, independent decelerating laser, with a profile mode matched to the atomic beam. For an oven temperature of 580±C this system can load 1.2 (2) x 10(7) atoms in 16 (1) ms. By the spatial extension of the atomic cloud the one dimension rms velocity was estimated to be 136 (12) cm/s, corresponding to a temperature of 9 (2) mK. The variation of the number of trapped atoms as a function of laser detuning and intensity, trap magnetic field gradient and oven temperature is analyzed. Spatial structures of the trapped atoms, like stable rings created by vortex forces, have been observed. This is the first time that these structures, already observed in alkali-metal elements, are reported in MOTs of alkaline-earth elements.332355362FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOSem informaçãoSem informaçãoSem informaçãoWe would like to acknowledge the glass shop of the UNICAMP Physics Institute for the very well done work in the construction of the atomic beam and MOT glass chamber. We also would like to thank the machine shop and J.B.Rodrigues for the mechanical parts. This work was supported by FAPESP, CAPES and CNPq and FAEPUNICAMP, Brazilian government agencies. Support for RLCF was through CAPES graduate research scholarship and for DAM and DRO through FAPESP graduate and undergraduate scholarships respectively

Valence and inner electronic excitation, ionization, and fragmentation of perfluoropropionic acid

The photoexcitation, photoionization, and photofragmentation of gaseous CF3CF2C(O)OH were studied by means of synchrotron radiation in the valence and inner energy regions. Photofragmentation events were detected from 11.7 eV through formation of COH+, C2F4+, and the parent species M+. Because the vertical ionization potential has been reported at 11.94 eV, the starting energy used in this study, 11.7 eV, falls just inside of the tail of the ionization band in the photoelectron spectra. Information from the total ion yield spectra around the C 1s, O 1s, and F 1s ionization potentials allows the energies at which different resonance transitions take place in the molecule to be determined. These transitions have been assigned by comparison with the results of the analysis of similar compounds. In the inner energy region, both kinetic energy release (KER) values and the slope and shape of double coincidence islands obtained from photoelectron–photoion–photoion coincidence (PEPIPICO) spectra allow different photofragmentation mechanisms to be elucidated.Centro de Química Inorgánic

Electronic properties of FC(O)SCH2CH3: a combined Helium(I) photoelectron spectroscopy and synchrotron radiation study

The valence electronic properties of S-ethyl flouromethanethioate (S-ethyl fluoromethsanethioate), FC(O)SCH2CH3, were investigated by means of He(I) photoelectron spectroscopy in conjunction with the analysis of the photofragmentation products determined by PEPICO (phtoelectron-photoion- coincidence) by using synchrotron radiation in the 11.1-21.6 eV photon energy range. The first band observed at 10.28 eV in the HeI photoelectron spectrum can be assigned with confidence to the ionization process from the HOMO [n π(S) orbital], which is described as a lone pair formally localized on the sulfur atom, in agreement with quantum chemical calculations using the outer valence Green function method [OVGF/6-311++G (d,p)]. One of the most important fragmentation channels also observed in the valence region corresponds to the decarbonylation process yielding the [M-CO] ·+ ion, which is clearly observed at m/z = 80. Moreover, S 2p and S 2s absorption edges have been examined by measuring the total ion yield spectra in the 160-240 eV region using variable synchrotron radiation. The dynamic of ionic fragmentation following the Auger electronic decay has been evaluated with the help of the PEPIPICO (photoion-photoion-photoelectron- coincidence spectra) technique.Centro de Química Inorgánic

Ionic fragmentation mechanisms of 2,2,2-trifluoroethanol following excitation with synchrotron radiation

Gaseous 2,2,2-trifluoroethanol (TFE) is excited with synchrotron radiation between 10 and 1000 eV and the ejected electrons and positive ions are detected in coincidence. In the valence-electron energy region, the most abundant species is CH2OH+. Other fragments, including ions produced by atomic rearrangements, are also detected; the most abundant are COH+, CFH2 + and CF2H2 +. The energies of electronic transitions from C 1s, O 1s and F 1s orbitals to vacant molecular orbitals are determined. A site-specific C 1s excitation is observed. The photofragmentation mechanisms after the excitation of core-shell electrons are inferred from analysis of the shape and slope of the coincidence between two charged fragments in the bi-dimensional coincidence spectra. The spectra are dominated by islands that correspond to the coincidence of H+ with several charged fragments. One of the most important channels leads to the formation of CH2OH+ and CF3 + in a concerted mechanism.Fil: Bava, Yanina Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica ; ArgentinaFil: Berrueta Martinez, Yanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica ; ArgentinaFil: Moreno Betancourt, Angelica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica ; ArgentinaFil: Erben, Mauricio Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica ; ArgentinaFil: Cavasso Filho, Reinaldo L.. Universidade Federal Do Abc; BrasilFil: Della Védova, Carlos Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica ; ArgentinaFil: Romano, Rosana Mariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica ; Argentin

Electronic properties of FC(O)SCH2CH3: A combined helium(I) photoelectron spectroscopy and synchrotron radiation study

The valence electronic properties of S-ethyl flouromethanethioate (S-ethyl fluoromethsanethioate), FC(O)SCH2CH3, were investigated by means of He(I) photoelectron spectroscopy in conjunction with the analysis of the photofragmentation products determined by PEPICO (phtoelectron-photoion- coincidence) by using synchrotron radiation in the 11.1-21.6 eV photon energy range. The first band observed at 10.28 eV in the HeI photoelectron spectrum can be assigned with confidence to the ionization process from the HOMO [n π(S) orbital], which is described as a lone pair formally localized on the sulfur atom, in agreement with quantum chemical calculations using the outer valence Green function method [OVGF/6-311++G (d,p)]. One of the most important fragmentation channels also observed in the valence region corresponds to the decarbonylation process yielding the [M-CO] ·+ ion, which is clearly observed at m/z = 80. Moreover, S 2p and S 2s absorption edges have been examined by measuring the total ion yield spectra in the 160-240 eV region using variable synchrotron radiation. The dynamic of ionic fragmentation following the Auger electronic decay has been evaluated with the help of the PEPIPICO (photoion-photoion-photoelectron- coincidence spectra) technique.Fil: Rodriguez Pirani, Lucas Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Erben, Mauricio Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Gerones, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Romano, Rosana Mariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Cavasso Filho, Reinaldo L.. Universidade Federal Do Abc;Fil: Ma, Chunping. Institute Of Chemistry Chinese Academy Of Sciences; ChinaFil: Ge, Maofa. Institute Of Chemistry Chinese Academy Of Sciences; ChinaFil: Della Védova, Carlos Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; Argentin

Two-Photon Doppler cooling of alkaline-earth-metal and ytterbium atoms

A new possibility of laser cooling of alkaline-earth-metal and Ytterbium atoms using a two-photon transition is analyzed. We consider a $^{1}S_{0}$ - $^{1}S_{0}$ transition, with excitation in near resonance with the $^{1}P_{1}$ level. This greatly increases the two-photon transition rate, allowing an effective transfer of momentum. The experimental implementation of this technique is discussed and we show that for Calcium, for example, two-photon cooling can be used to achieve a Doppler limit of 123 microKelvin. The efficiency of this cooling scheme and the main loss mechanisms are analyzed.Comment: 7 pages, 5 figure

Observing negligible collision trap losses: the case of alkaline-earth metals

FAPESP - FUNDAÇÃO DE AMPARO A PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOWe show that when cold collisions account for just a few percent of the total loss in magneto-optical traps, as for alkaline-earth metals, their contribution can be obtained by comparing the load and decay quasiexponential curves. We exemplify it by measuring the collision rate coefficient beta for calcium atoms at small trap laser detuning, which confirms the role of the long-lived (1)Pi(g) state at small internuclear separation. Systematic and simpler measurements of beta for alkaline-earth metals are important for cold collision theory, since these elements have nondegenerate ground state and no hyperfine structure. Our method has general applicability and should considerably reduce the experimental challenges associated with these important measurements.67214FAPESP - FUNDAÇÃO DE AMPARO A PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO A PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGIC

Frequency doubled and stabilized all-solid-state Ti : sapphire lasers

FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORWe describe in detail the design, construction, and characterization of an efficient frequency doubled and stabilized all-solid-state Ti:sapphire laser. The laser frequency has been locked to the resonance of a Fabry-Perot cavity, and doubled in a Brewster-cut potassium niobate crystal placed inside a power enhancement cavity. Up to 200 mW of single frequency blue light with fast frequency instabilities of 40-kHz rms and a drift of 10 MHz/hour has been generated. The spectral distributions of amplitude and frequency noise for the free-running laser have been measured and compared with the case of pumping from an argon ion laser. Our laser is well suited in atomic physics for high resolution spectroscopy and for laser cooling and trapping using transitions in the blue-violet region, as we demonstrate with the calcium resonant transition, at 423 nm.We describe in detail the design, construction, and characterization of an efficient frequency doubled and stabilized all-solid-state Ti:sapphire laser. The laser frequency has been locked to the resonance of a Fabry-Perot cavity, and doubled in a Brewster-cut potassium niobate crystal placed inside a power enhancement cavity. Up to 200 mW of single frequency blue light with fast frequency instabilities of 40-kHz rms and a drift of 10 MHz/hour has been generated. The spectral distributions of amplitude and frequency noise for the free-running laser have been measured and compared with the case of pumping from an argon ion laser. Our laser is well suited in atomic physics for high resolution spectroscopy and for laser cooling and trapping using transitions in the blue-violet region, as we demonstrate with the calcium resonant transition, at 423 nm.41511221127FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORSem informaçãoSem informaçãoSem informaçãoThis work was supported by FAPESP, CNPq, and CAPES, Brazilian government agencies. We would like to thank Jim Bergquist for many of the design concepts used by us and for the continuing assistance and support; V.S. Bagnato, L.G. Marcassa, and S.C. Zilio for supplying Ti:Al2O3, a TGG crystal, and the mirrors from the University of São Carlos Optics Workshop (Brazil); Nelson B. Sales, Jorge L. Pires, Antônio J. Polaquini, and João B. Rodrigues for the mechanical parts

Interstellar H3+ and HCS+ Ions Produced in the Dissociative Photoionization Process of CH3C(O)SCH3 in the Proximity of the Sulfur 2p, Carbon 1s, and Oxygen 1s Edges

In this work we present a study of the dissociative photoionization of S-methyl thioacetate [CH3C(O)SCH3] by using multicoincidence time-of-flight mass spectrometry and synchrotron radiation in the S 2p, C 1s, and O 1s edges. Total and partial ion yield spectra together with photoelectron–photoion coincidence (PEPICO) and photoelectron–photoion–photoion coincidence (PEPIPICO) spectra were measured. Fragmentation patterns deduced from PEPICO and PEPIPICO spectra at the various excitation energies show a moderate site-specific fragmentation. The dissociation dynamic for the main ion-pair production is discussed. Two-, three-, and four-body dissociation channels have been observed in the PEPIPICO spectra, and the dissociation mechanisms are proposed. The interstellar HCS+ and H3+ ions can be observed during the synchrotron experiments reported in the present work.Fil: Gerones, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Erben, Mauricio Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Romano, Rosana Mariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Cavasso Filho, Reinaldo L.. Universidade Federal do ABC; BrasilFil: Della Vedova, Carlos Omar. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin