Josél. Alonso

Universidad de Valladolid, Valladolid, Castile and Leon, Spain

Are you Josél. Alonso?

Claim your profile

Publications (8)12 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The rotational spectrum of the van der Waals complex consisting of argon and 2,5-dihydrofuran has been observed in a molecular beam Fourier transform microwave spectrometer in the frequency range 5–18.5 GHz. Analysis of the derived spectroscopic constants shows that the dimer has a structure with a plane of symmetry in which the argon atom is located 3.48 Å above the ring plane. The experimental setup of the molecular beam Fourier transform microwave spectrometer is also presented.
    Chemical Physics 06/1997; · 1.96 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The rotational spectra of 2-methyloxetane and 3-methyloxetane have been reinvestigated using Fourier transform microwave spectroscopy (FTMW). A,E splittings due to internal rotation of the methyl group have been observed in the ground and several ring-puckering and methyl torsion excited states for both molecules. Internal rotation barriers of V3 = 3.332(14) kcal mol−1 (13.941(58) kJ mol−1) for 2-methyloxetane and V3 = 3.284(12) kcal mol−1 (13.740(50) kJ mol−1) for 3-methyloxetane have been determined from the ground vibrational state spectra. Furthermore, the rotational, quartic and some higher-order centrifugal distortion constants are reported. The experimental set-up of a waveguide Fourier transform microwave spectrometer is also presented.
    Chemical Physics 01/1996; · 1.96 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The microwave (MW) spectrum of 1-nitropyrazole obtained at room temperature is presented, together with ab initio MP2/6-31G∗∗ calculations on its structure and harmonic vibrational frequencies. The initial assignment of the spectrum was carried out using a radio frequency—microwave double resonance (RFMWDR) technique. Both experimental and theoretical results indicate that 1-nitropyrazole is a planar molecule. The structure obtained from the MW spectrum agrees fairly well with that obtained at the MP2(FULL)/6-31G∗∗ level.
    Journal of Molecular Structure 01/1995; 344(3):241-250. · 1.40 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The rotational spectra of cyclobutanone in the ground and the first seven excited states of the ring-puckering vibration, nu27, have been measured in the frequency range 18-250 GHz. The spectra of the ring-puckering excited states with v27 = 8, 9, and 10 and of 11 vibrational excited states belonging to ring-puckering progressions based on the first excited states of the out-of-plane, nu26, and in-plane, nu20, carbonyl bending vibrations have been measured in the frequency range 18-50 GHz. The dependence of the rotational and centrifugal distortion constants on the ring-puckering quantum number has been analyzed in terms of two different reduced ring-puckering potential functions: a mixed quadratic-quartic function and a harmonic oscillator perturbed by a quartic and a Gaussian term. This analysis shows that a one-dimensional model for the ring-puckering is only adequate to describe the features of the low energy levels of this vibration.
    Journal of Molecular Spectroscopy 12/1992; 156(2):341-359. · 1.67 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Microwave measurements on the ground and first eight excited states of the ring-puckering vibration of butadiene sulfone have been extended to millimeter wavelengths. The microwave spectra of the same vibrational states of alpha,alpha'-D4 butadiene sulfone have been observed. For both isotopomers the Coriolis interaction between the v = 0 and v = 1 states has been analyzed to give the energy separation between these two states. These data and the variation of the rotational constants have been used to derive reduced potential functions for the ring-puckering vibration. The barrier to ring inversion is 49(2) cm-1 for butadiene sulfone and 44(2) cm-1 for the alpha,alpha'-D4 isotopomer. The ring-puckering vibrational dependence of the quartic centrifugal distortion constants, including a small dependence of DeltaJ and deltaJ, has been accounted for.
    Journal of Molecular Spectroscopy 10/1991; 149:317-328. · 1.67 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Microwave measurements on the ground and first eight excited states of the ring-puckering vibration of butadiene sulfone have been extended to millimeter wavelengths. The microwave spectra of the same vibrational states of α,α′-D4 butadiene sulfone have been observed. For both isotopomers the Coriolis interaction between the v = 0 and v = 1 states has been analyzed to give the energy separation between these two states. These data and the variation of the rotational constants have been used to derive reduced potential functions for the ring-puckering vibration. The barrier to ring inversion is 49(2) cm−1 for butadiene sulfone and 44(2) cm−1 for the α,α′-D4 isotopomer. The ring-puckering vibrational dependence of the quartic centrifugal distortion constants, including a small dependence of ΔJ and δJ, has been accounted for.
    Journal of Molecular Spectroscopy 01/1991; · 1.67 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The microwave spectrum of 1-nitrocyclohexene has been recorded in the frequency region 26.5-40 GHz. Rotational transitions have been assigned for the vibrational ground state, the first six torsionally excited states, and some excited states involving the lowest skeletal ring modes. A model calculation to reproduce the ground state rotational constants and the inertia defect value indicates that the data are consistent with a twisted ring conformation. From the energy spacing determined from relative intensity measurements a barrier for the internal rotation has been estimated.
    Journal of Molecular Spectroscopy 01/1989; 133(2):413-422. · 1.67 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The microwave spectrum of alpha-methyl-gamma-butyrolactone has been examined in the frequency region 18.0-40.0 GHz. Transitions in the ground and four excited states have been assigned for a ring-twisted-like conformation species in which the methyl group is in the equatorial position. Internal rotation splittings were absent in all observed transitions (up to J = 38), which implies a lower limit for the barrier of ~3.5 kcal mol-1. The dipole moment components determined from Stark effect measurements are mua = 1.21(2) D, mub = 4.36(5) D, and muc = 0.573(3) D, with mutotal = 4.56(5) D. Despite an intensive effort, no transitions belonging to another species could be identified. A preliminary description of a computer-controlled spectrometer is also given.
    Journal of Molecular Spectroscopy - J MOL SPECTROSC. 01/1988; 131:9-20.