An Nd:YAG single pulse nanosecond laser of 532 nm wavelength with an 8 ns pulse width was projected on the soil samples collected from the campus of Bengbu College under 1 standard atmospheric pressure. Laser-induced breakdown spectroscopy at different sample temperatures was achieved. The intensity and signal-to-noise ratio (SNR) changes of dif­ferent characteristic spectral lines could be analyzed when the sample temperature changes. The evolution of plasma electron temperature and electron density with the sample temper­ature was analyzed through Boltzmann oblique line method and Stark broadening method. The cause of the radiation enhancement of laser-induced metal plasma was discussed. Ex­perimental results demonstrated that the spectral intensity, SNR, the electron temperature and electron density of plasma are positively related to the sample temperature, and reach saturation at 100 °C.

In the present paper, a detailed analysis is given for the study of antihydrogen formation in P + P s collisions in the presence of a purely monochromatic, linearly polarized laser field. The dressing effects are considered by the treatment of the dipole approximation and the perturbation approach up to first order. The angular distributions have been calculated for a few typical cases. It is shown that laser fields can produce significant modifications on the angular distributions.

AbstractFruit is not only delicious, but it also contains iron, potassium, magnesium, and other microelements necessary for the human body. Banana, pineapple and kiwifruit were selected as samples for testing. A laser with a wavelength of 532 nm was focused on the samples’ surface to generate a plasma. The emission spectrum of the atoms and ions in the plasma were collected by optical receivers, and the optimal condition was confirmed by analyzing the signal-to-noise ratio. The electronic temperature characteristics of the Fe plasma were studied under optimal experimental conditions. The maximum electron temperature of the Fe plasma occurred after a time delay of 300 ns in bananas, after 400 ns in pineapples and after 400 ns in kiwifruit. The electronic temperature of the Fe plasma increased with the time delay before the maximum point was reached. However, the temperature decreased after the maximum point was reached. At the beginning of the decline, the plasma decreased rapidly, but later decreased slowly. The range of the variation of the electron temperature of the Fe plasma in bananas, pineapples, and kiwifruits was 12388.29–19958.3 K, 11994.21–16856.4 K, and 13388.2–19607.32 K, respectively.