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An investigation was made into the interaction of Q-switched Nd: glass laser pulses, with energies of 5–100 J and intensities in the range of 1–15 GW cm−2, with thin slab samples of basalt, in a geometry in which the laser–matter interaction was enhanced by confining the laser-induced plasma and vapor against the rock surface with a thin water layer. The high pressure generated during expansion of the ablated material produced a shock wave which traveled into the rock. On basalt samples of thicknesses of up to 18 mm, reflection of the shock wave at the rear surface of the sample caused a thin rock layer to be spalled. Examination of the structure within the interior of the rock after laser exposure revealed extensive grain disruption near to the laser spot, due to the shock-wave passage. Rock specimens of thickness 50 mm were tested via Vickers hardness microindenter. The laser exposure was shown to produce a hardness decrease within the rock which was up to 50%, and extended to depths of 25 mm beneath the target position. An empirical model accounting for shock-wave formation and propagation was developed and compared to the experimental results.

We report an experimental investigation of absorption, fluorescence, and nonlinear absorption in a platinum-ethynyl complex. We have observed strong singlet absorption at 355 nm, and a weaker triplet absorption at 520 nm. Photoluminescence measurements show a fluorescence band at 400 nm and a phosphorescence band at 520 nm. Pump–probe nonlinear absorption measurements confirmed that S0→T1 followed by excited triplet-state absorption corresponds to the dominant excitation path in the region between 513 and 532 nm.

Differential cross sections for the (..pi../sup -/,n) reactions in /sup 3/He and /sup 4/He have been measured at energies of 100, 200, and 290 MeV. The angular distributions for /sup 3/He and /sup 4/He are different, with the /sup 4/He characterized by an oscillatory pattern with a dip at a fixed angle of approx. = 70/sup 0/. The forward-angle cross sections show a simple dependence upon momentum transfer for both /sup 3/He and /sup 4/He. These results are discussed in the context of single-nucleon and multinucleon reaction diagrams.

Differential cross sections for the reaction /sup 3/He(..pi../sup -/,..pi../sup 0/)/sup 3/H at energies of 200, 250, 275, and 290 MeV over the angular region 80 /sup 0/ < or approx. = theta/sub c.m./ < or approx. = 150/sup 0/ are presented. Comparison is made with theoretical predictions based on Glauber theory and optical-potential calculations. Neither approach gives a satisfactory description on the data; in particular, the observed energy dependence is much smaller than the theoretical predictions.

Outgoing-nucleon charge exchange has been used to explain reduction in ..pi..-N isospin selectivity in a large number of nucleon-removal experiments. The present work tests the validity of this model by measuring the total cross sections for nucleon removal to the 4.44-MeV, T = 0 and the 15.11-MeV, T = 1 states in /sup 12/C, where analog charge exchange is possible for the latter, but not the former state.

Initial high resolution measurements of projectile electron emission spectra for beam gas collisions are reported. The Auger electron decay of beams of O + , O 2+ , and O 3+ at 3, 8, and 18 MeV, respectively, excited by single collisions with He, Ne, and Ar was measured at a lab emission angle of 23.7° with a 36 cm double focussing electrostatic analyzer. Although prompt transitions are found to predominate the spectra, several weak lines are attributed to transitions from metastable states. Spectral features are seen to vary greatly as a function of exciter gas and as a function of projectile charge state and energy.

Total cross sections for the knockout reactions $^{7}\mathrm{Li}({\ensuremath{\pi}}^{\ensuremath{-}},{\ensuremath{\pi}}^{\ensuremath{-}}n)^{6}\mathrm{Li}$ and $^{7}\mathrm{Li}({\ensuremath{\pi}}^{+},{\ensuremath{\pi}}^{+}n)^{6}\mathrm{Li}$ to 3.56-MeV ${0}^{+}$ $T=1$ state have been measured at ten energies between 50 and 290 MeV by detecting the direct $\ensuremath{\gamma}$ de-excitation. As found in previous work, the ratio $\frac{\ensuremath{\sigma}({\ensuremath{\pi}}^{\ensuremath{-}},{\ensuremath{\pi}}^{\ensuremath{-}}n)}{\ensuremath{\sigma}({\ensuremath{\pi}}^{+},{\ensuremath{\pi}}^{+}n)}$ on the (3,3) resonance is significantly less than the value of 3 expected from free pion-nucleon results.

Targets of Al and Al2O3 were bombarded by 0.8 MeV protons and 3.2 MeV alpha particles and the subsequent X-ray yield measured. The Kα X-ray spectra of Al and Al2O3 show fairly good agreement in both the proton and alpha-induced spectra; however, the structure in the Kβ X-ray spectra deviate from one another in both cases. These results are interpreted as effects due to the chemical bonding of the oxygen atoms to aluminum.

Four equidistant peaks are observed below the Kα 1,2 line in the X-ray spectra of Na, Al, Si, SiO 2 , Ca, Sc and Ti, produced by oxygen bombardment. With much weaker intensity, these lines are also seen in proton excitation. The lines are interpreted to be due to the excitation of one or more volume plasmons in the target material by the Kα 1,2 X-ray decay.