MOLECULAR BEAM VISIBLE-LASER SPECTROSCOPY OF 11BO2^{11}BO_{2}

$^{1}$ R.S. Lowe, H. Gerhardt. W. Dillenschneider. R.F. Curl. Jr. and F.K. Tittel, J. Chem. Phys. 70,42 (1979). $^{2}$ A.G. Adam, A.J. Merer and D.M. Steunenberg, J. Chem. Phys. in press.Author Institution: Department of Chemistry, University of British Columbia; Department of Physics, University of British ColumbiaThe hyperfine structures of various lines in the $$ band of the $\bar{A}^{2}\Pi_{u}-\bar{X}^{2}\Pi_{g}$ system of $^{11}BO_{2}$, near 5450 {\AA}, have been recorded at very high resolution using molecular beam laser techniques. The results supplement the earlier R-branch measurements of Curl $et al^{1}$, which were taken using intermodulated fluorescence. In particular they show previously-unsuspected perturbations in the upper state hyperfine patterns at many of the places where the rotational lines have recently been found to be slightly $shifted^{2}$. Ground state parameters have been extracted from the combination differences, but no simple model can be devised to fit the upper state, which turns out to be randomly perturbed as a result of extensive vibronic coupling with high vibrational levels of the ground state

LASER-INDUCED FLUORESCENCE MOLECULAR-BEAM OBSERVATIONS OF THE HYPERFINE STRUCTURE IN THE NO2NO_{2} SPECTRUM AT 593.5 nM AND 585.1 nm

$^{1}$ R.Smalley, L.Wharton and D.Levy. J.Chem.Phys. 63. 4977(1975). $^{2}$ (a)T.Tanaka and D.Harris. J.Mol.Spectrosc. 59. 413(1976). (b)G.Persch, H. Vedder and W.Demtroder. J.Mol.Spectrose. 123, 356(1987). $^{3}$ S.Coy, K.Lehmann and F.DeLucia. J.Chem.Phys. 85 4296(1986).Author Institution: Chem. Dept., 2036 Main Mail, U.B.C., Vancouver; Physics Dept., 6224 Agriculture Rd., U.B.C.While testing a wavelength calbration system for molecular beam work in the visible region we have measured the hyperfine structures of the $K=0$ bands at 593.5 nm and 585.1 mi In the spectrum of jet-cooled $NO_{2}$ (bands 99 and 115 of Smalley $et al.^{1}$). Linewidths of 10 MHz were obtained typically: for the strongest lines these could be reduced to 2 MHz by a Lamb-dip technique to resolve closely spaced components. The calibration system allowed the hyperf ins splittings of a rotational line to be measured to $\pm 1 MHz$, while giving agreement to $\pm 10 MHz$ between $\Delta_{2}F^{\prime\prime}(N)$ combitiation differences measured from the optical spectrum and calculated from the microwave spectrum. The N. J.and F assignments could then be made unambiguously without the need for wavelength-resolved fluorescence. Values for the electron spin-rotation, Fermi contact and (1.5) dipolar parameters were obtained for the $^{2}B_{2}$ upper levels with $N=1,3,\ldots 9$. Good agreement was obtained with literature $values^{2}$ where they exist. We find that the spectrum in this region consists of individual subbands which can each be approximately described by a single set of constants, though the density of local perturbations requires that the structure of each N' level be treated separately. It seems that the apparently contradicting descriptions of the spectrum given by Lehmann $et al.^{3}$ and Demtroder $et al.^{2}$ are not Inconsistent with each other, but represent different viewpoints of the same perturbed system

Diastolic ventricular interaction:from physiology to clinical practice

The ventricles share a common septum and, therefore, the filling of one influences the compliance of the other. This phenomenon is known as direct diastolic ventricular interaction. The interaction is noticeably increased when the force exerted by the surrounding pericardium is raised, which is termed pericardial constraint. In healthy individuals, pericardial constraint is minor in the resting state. When right ventricular volume-to-pressure ratio acutely increases, however, such as during exercise, massive pulmonary embolism, or right ventricular infarction, notable diastolic ventricular interaction occurs. In this setting, the measured left ventricular intracavitary diastolic pressure overestimates the true left ventricular filling pressure, because the effect of external forces must be subtracted. Although growth of the pericardium can be a feature of chronic cardiac enlargement, here we review the evidence of the importance of diastolic ventricular interaction in certain acute and chronic disease processes, including heart failure