S. Kubodera

Autofluorescence maps of atherosclerotic human arteries--A new technique in medical imaging

A new medical imaging technique for arterial walls based on laser-induced autoflnorescence spectroscopy is reported. The internal surface of isolated arteries with or without atherosclerosis is irradiated with an argon ion laser (458 nm) and the peak intensity of the excited autofluorescence spectrum is related to the composition of the arterial wall. The higher autofluorescence intensity in the range between approximately 480 and 630 nm for grossly calcified tissue compared to normal or noncalcified atherosclerotic tissue is used to produce maps of the arterial wall. These images delineate the calcified areas of the sample with good spatial resolution. If this technique can be adapted to the endoscopic visualization of arteries in vivo (angios, Copy), it could become an important tool for the diagnosis of atherosclerosis and for the monitoring of atheroma ablation during laser angioplasty.

Emission from ionic cesium fluoride excimers excited by a laser-produced plasma

CsF vapor generated in a heat pipe was excited by a laser-produced plasma. Temporally integrated spectra and time-resolved fluorescence on the ionic excimer transition Cs(2+)F(-) ? Cs(+)F were observed at 185 nm. The pressure dependence of the fluorescence is influenced by self-absorption in the CsF vapor. The fluorescence is assigned to the Cs(2+)F(-) ((2)Sigma(1/2), B)? Cs(+)F ((2)Sigma(1/2),X) transition.

Absorption spectra of alkali halide molecules in the vacuum ultraviolet

The ultraviolet (UV) and vacuum ultraviolet (VUV) absorption spectra of three alkali halide molecules CsF, CsCl, and RbF have been determined experimentally. The longest wavelength absorption features are attributed to bound–free or bound–weakly bound transitions where the upper state correlates to ground state alkali and halogen atoms. The absorption at shorter wavelengths is due to transitions from the bound ground state to excited states that correlate to excited alkali and neutral halogen atoms. The covalent repulsive curves of CsF were found to have a close resemblance to the curve corresponding to the first ionization potential of CsF. The peak absorption cross sections are similar for the CsF and RbF molecules. CsCl molecules have a three to four times larger absorption cross section for the analogous upper states. The absorption oscillator strengths have been determined from the measured absorption cross sections, and are compared to those of other alkali halide molecules that have UV absorptions.

Characterization of plasmas from a pulsed jet discharge for applications VUV spectroscopy and micromechanics

Plasmas from a pulsed jet discharge have been characterized with respect to gas species and nozzle design. Spectral lines from the gas used in the pulsed nozzle are apparent in the visible region. The vacuum ultraviolet spectrum, particularly for heavier gases, is dominated by emission from species sputtered from the nozzle. The production of highly ionized and excited states from materials created by the sputtering of the nozzle has possible applications in VUV (vacuum ultraviolet) spectroscopy. Operating the pulsed jet discharge at a 50-Hz repetition rate with NF/sub 3/ to produce excited fluorine ions allowed etch rates in excess of 10 mu m/min to be achieved in silicon; this may have applications to micromechanics. >

Ionic alkali halide excimers excited by a laser‐produced plasma

We have observed ultraviolet (UV) and vacuum ultraviolet (VUV) emission from ionic alkali halide molecules and ionic rare gas alkali metal molecules excited by the soft x‐rays from a laser‐produced plasma and relativistic electron beams. The excitation process of the ionic excimer has been investigated using a simple kinetic model. The emission behavior of those ionic excimers in the UV and VUV region has been experimentally studied.