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1.
Jastrzebski W Kowalczyk P Camacho JJ Pardo A Poyato JM 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2001,57(9):1829-1831
The C1pi(u) <-- X1sigma(g)+ system of Na2 is studied by the polarization labelling spectroscopy technique. Accurate molecular constants are derived for the observed levels nu = 0-12, J = 12-100 in the C1pi(u) state. 相似文献
2.
V. Balek L. A. Pérez-Maqueda J. Poyato Z. Černý V. Ramírez-Valle I. M. Buntseva J. L. Pérez-Rodríguez 《Journal of Thermal Analysis and Calorimetry》2007,88(1):87-91
The effect of grinding
on thermal behavior of pyrophyllite and talc as commonly used ceramic clay
minerals was investigated by DTA, TG, emanation thermal analysis (ETA), B.E.T.
surface area (s.a.) measurements, X-ray diffraction (XRD) and scanning electron
microscopy (SEM).
A vibratory mill was used in this study, grinding
time was 5 min. It was found that the grinding caused an increase in surface
area and a grain size reduction of the samples. From TG and DTA results it
followed that grinding caused a decrease of the temperature at which the structure
bound OH groups released. The formation of high temperature phases was enhanced
with the ground samples. For the ground talc sample the crystallization of
non-crystalline phase into orthorhombic enstatite was observed in the range
of 800°C. For ground pyrophyllite a certain agglomeration of grains was
observed in the range above 950°C. Moreover, for both clays the ETA characterized
a closing up of subsurface irregularities caused by grinding as a decrease
of the emanation rate in the range 250–400°C. The comparison of
thermal analysis results with the results of other methods made it possible
to better understand the effect of grinding on the ceramic clays. 相似文献
3.
R. PereiraS. Skowronek A.González Ureña A. PardoJ.M.L. Poyato A.H. Pardo 《Journal of Molecular Spectroscopy》2002,212(1):17-21
Rotationally resolved spectra of the CaH radical using a supersonic molecular beam are reported. Thus, high energy resolution of the (1+1′) REMPI spectra corresponding to the A←X and B←X electronic transitions were measured which allowed for the first time a clear and precise analysis of the low rotational part (J≤7) of the CaH spectrum. A comparison with previous studies revealed that the commonly accepted energy separation between the two band heads of B−X (v′=1, v′=0) of 10 cm−1 is not correct. A value of ca. 1.6 cm−1 was found to be more realistic. On the other hand, the present study confirmed that the perturbation appears only for v′=1, N′>3 of the B state. 相似文献
4.
A. Pardo E. Martin J. M. L. Poyato J. J. Camacho 《Journal of photochemistry and photobiology. A, Chemistry》1987,41(1)
The synthesis and photophysical properties of some 3-amino-N-substituted-1,8-naphthalimide derivatives are presented. The flourescence behaviour of these compounds in protic and aprotic solutions is consistent with the formation of an exciplex structure. The exciplex formation is due to a proton transfer in the excited state. This exciplex formation eliminates non-radiative channels and therefore an increase in quantum yield is observed. 相似文献
5.
J.J. Camacho L. DíazM. Santos J.M.L. Poyato 《Spectrochimica Acta Part B: Atomic Spectroscopy》2011,66(1):57-66
Laser-induced breakdown spectroscopy of helium plasma, initially at room temperature and pressures ranging from 12 to 101 kPa was investigated using a transverse excitation atmospheric CO2 pulsed laser (λ = 9.621 and 10.591 μm, a full width at half maximum of 64 ns, and an intensity from 1.5 to 5.36 GW cm−2). The helium breakdown spectrum is mainly due to electronic relaxation of excited He, He+ and H. Plasma characteristics were examined in detail on the emission lines of He and He+ by the time-integrated and time-resolved optical emission spectroscopy technique. Optical breakdown threshold intensities, ionization degree and plasma temperatures were obtained. An auxiliary metal mesh target was used to analyze the temporal evolution of the species in the plasma. The results show a faster decay of the continuum emission and He+ species than in the case of neutral He atoms. The velocity and kinetic energy distributions for He and He+ species were obtained from time-of-flight measurements. Electron density in the laser-induced plasma was estimated from the analysis of spectral data at various times from the laser pulse incidence. Temporal evolution of electron density has been used for the estimation of the three-body electron-ion recombination rate constant. 相似文献
6.
J. J. Camacho M. Santos L. Díaz J. M. L. Poyato 《Applied Physics A: Materials Science & Processing》2009,94(2):373-380
We have used ferrocene and paraffin wax as novel precursor and solvent for the growth of iron oxide nanoparticles. The proposed
method of growth has several advantages over existing methods of growth using iron pentacarbonyl a precursor. Highly crystalline
and monodispersed particles are obtained which assemble in two- and three-dimensional hexagonal closed packed superlattices.
Growth kinetics has been studied by varying concentration of the precursor and time of growth. A phenomenological model has
been proposed to explain the growth kinetics. 相似文献
7.
8.
Camacho JJ Santiago J Pardo A Reyman D Poyato JM 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2000,56(4):769-781
The fluorescence spectrum of Na2 induced by the 4879.86 A line of an Argon ion laser has been analyzed with special emphasis on determination of accurate relative intensities. We have observed nineteen fluorescence series for the B1pi(u) --> X1sigma(g)+ band system. Some series are reported for the first time. The radiative transition probabilities for the observed fluorescence series were calculated using hybrid potential energy curves for the B1pi(u) and X1sigma(g)+ states constructed up to dissociation and a B-X transition dipole moment function. Radiative lifetimes for the rovibrational levels of the upper states pumped by the laser line have also been calculated. The transition probabilities and lifetimes agree with the corresponding observed measurements usually within the experimental uncertainty. From the rotational satellite structure with deltaJ' = +/- 1, +/- 2...+/- 20, for some nu'-bands of the most intense fluorescence series induced by emission from the vibrational-rotational levels: nu' = 6, J' = 43 and v' = 9, J' = 56, collision-induced transition rates and average cross sections have been obtained. 相似文献
9.
J. J. Camacho M. Santos L. Díaz L. J. Juan J. M. L. Poyato 《Applied Physics A: Materials Science & Processing》2010,99(1):159-175
A spectroscopic study of ambient air plasma, initially at room temperature and pressures ranging from 32 to 101 kPa, produced
by high-power transverse excitation atmospheric (TEA) CO2 laser (λ=9.621 and 10.591 μm; τ
FWHM≈64 ns; power densities ranging from 0.29 to 6.31 GW cm−2) has been carried out in an attempt to clarify the processes involved in laser-induced breakdown (LIB) air plasma. The strong
emission observed in the plasma region is mainly due to electronic relaxation of excited N, O and ionic fragments N+. The medium-weak emission is due to excited species O+, N2+, O2+, C, C+, C2+, H, Ar and molecular band systems of N
2+(_{2}^{+}(
B
2\varSigma u+^{2}\varSigma _{\mathrm{u}}^{+}
–X
2\varSigma g+)^{2}\varSigma _{\mathrm{g}}^{+})
, N2(C3
Π
u–B3
Π
g), N
2+(_{2}^{+}(
D2
Π
g–A2
Π
u) and OH(A2
Σ
+–X2
Π). Excitation temperatures of 23400±700 K and 26600±1400 K were estimated by means of N+ and O+ ionic lines, respectively. Electron number densities of the order of (0.5–2.4)×1017 cm−3 and (0.6–7.5)×1017 cm−3 were deduced from the Stark broadening of several ionic N+ and O+ lines, respectively. Estimates of vibrational and rotational temperatures of N
2+_{2}^{+}
electronically excited species are reported. The characteristics of the spectral emission intensities from different species
have been investigated as functions of the air pressure and laser irradiance. Optical breakdown threshold intensities in air
at 10.591 μm have been measured. 相似文献
10.
M. Santos L. Díaz J. J. Camacho J. M. L. Poyato J. Pola T. Krenek 《Applied Physics A: Materials Science & Processing》2010,99(4):811-821
Laser-induced breakdown spectroscopy (LIBS) in germane (GeH4), initially at room temperature and pressures ranging from 2 to 10 kPa, was studied using a high-power transverse excitation
atmospheric (TEA) CO2 laser (λ=10.653 μm, τ
FWHM=64 ns and power densities ranging from 0.28 to 5.52 GW cm−2). The strong emission spectrum of the generated plasma is mainly due to electronic relaxation of excited Ge, H and ionic
fragments Ge+, Ge2+ and Ge3+. The weak emission is due to molecular bands of H2. Excitation temperatures of 8100±300 K and 23,500±2500 K were estimated by Ge atomic and Ge+ singly ionized lines, respectively. Electron number densities of the order of (0.7–6.2)×1017 cm−3 were deduced from the Stark broadening of several atomic Ge lines. The characteristics of the spectral emission intensities
from different species have been investigated as functions of the germane pressure and laser irradiance. Optical breakdown
threshold intensities in germane at 10.653 μm have been determined. The mechanism of initiation of the laser-induced plasma
in germane has been analyzed. 相似文献