Laser-irradiated clusters

The observation of blackbody-radiation-induced thermal dissociation of gaseous cluster ions suggests that very low power, CW infrared laser irradiation should also... 

Thin Sections or pieces of the rock about 1 mm in size or less can be also analyzed with this instrument at glancing incident irradiation, if the site to be analyzed is close to the surface of the section or the edge of a fraction. However in this mode of operation, mass resolution is severely reduced. Nevertheless ions can be identified because of their low mass numbers and the very low background in the spectra, by known cluster patterns or by comparison with reference spectra obtained with reduced laser irradiation. The spectra have shown to be highly reproducible. For more precise bulk. sample analysis, other instruments such as the LAMMA 1000 are more suited. Their lateral resolution is 1-3 pm in diameter and the depth of analysis is typically 0.1 pm. 

In this study, in order to better understand the fundamentals of the laser-cluster interaction, we have carried out systematic investigations of the properties of X-ray radiation from high-density and high-temperature cluster plasma created by the action of superintense laser irradiation. The interrelationship between the X-ray radiation properties and ion kinetic energies has been examined for the first time via simultaneous measurements of X-ray radiation spectra and ion energy spectra. The time scale and mechanism of the X-ray emission process are discussed here based on a time-dependent plasma kinetics model. Moreover, in order to demonstrate the practical capabilities of the X-rays thus produced, pulse X-ray diffraction from an Si crystal using this source has been examined. 

Fig. 12.3. a The time-integrated X-ray emission spectrum of laser-irradiated micron-sized Ar clusters measured at an intensity of 1.3 x 1019W/cm2, a pulse duration of 30fs, and a contrast ratio of C = 5 X 10-6. b Enlarged spectrum of a in the vicinity of the Li-like line structure... 

Systematic investigations of the laser-cluster interaction were carried out by simultaneously measuring high-resolution X-ray emission spectra and ion energy spectra produced by the laser irradiation of micron-sized Ar clusters at laser intensities of 1018 to 1019 W/cm2. To suppress the creation of preplasma, we designed a special conical nozzle and eliminated the laser prepulse. The results indicate that the explosion time scale for micron-sized clusters is much longer than that for nanometer-sized clusters. It is found that hot electrons produced by a higher contrast pulse (a smaller prepulse) allow the isochoric... 

Junkel-Vives GC, Abdallah Jr. J, Blasco F, Dorchies F, Caillaud T, Bonte C, Stenz C, Salin F, Faenov AYa, Magunov AI, Pikuz TA, Skobelev IYu (2002) Evidence of supercritical density in 45-fs-laser-irradiated Ar-cluster plasmas. Phys. Rev. A 66 0332041-0332045... 

Larsson J, Sjogren A (1999) Evaluation of laser-irradiated Ar clusters as a source for time-resolved X-ray studies. Rev. Sci. Instrum. 70 2253-2256... 

Microstructural changes of amorphous cartwn (a-C) and tetrahedrally amorphous carbon (ta-C) upon laser irradiation is studied in this paper. As it is shown, ta-C films with higher ratio of sp bonded carbon atoms are more stable compare to low density a-C films. The sjf bonded atoms in a-C films start clustering at laser energies lower than the energy needed for clustering of sp bonded atoms in ta-C films. 

Fig. 3 shows the Raman spectra of the as-deposited and laser irradiated a-C films deposited at 300 V substrate bias. The spectrum for the as-deposited sample can be fitted with a single BWF peak located at 1536.3 cm which corresponds to the presence of about 50% s[ bonded atoms. Laser irradiation with energies higher than 206 mJ/cm results in the formation of sp clusters which is significantly lower compare to the same energy required for sf clustering in high sp bonded films (Fig. 3B). 

Concurrently, the world of ultracold systems has expanded its boundaries during the last decade to encompass ultracold, three-dimensional, large hnite systems [e.g., ( He)jy clusters (N = 2-10" ), and ( He)jy clusters (N = 25-10 )] in the temperature range of T = 0.1-2.2 K [6-11, 50-78], finite optical molasses in laser irradiated ultracold atomic gases in the temperature range of 10-100 pK [79], as well as finite Bose-Einstein condensates in the temperature range of 10-100 nK [14, 80],... 

The neutral clusters, C6H4(OH)2 (H20),, are found to be produced in the gas phase by irradiation of the pulsed IR-laser onto the liquid beam. The clusters continue to be released from the liquid beam surface for a period of 10 ps after the pulsed IR-laser irradiation. The dynamics of the cluster release is further examined by observing the neutral species at a certain time after the IR-laser irradiation at a certain distance from the liquid beam. In reality, the neutral species are ionized by the pulsed UV-laser and are mass analyzed by the mass spectrometer. The spatial distribution of the neutral clusters are observed by changing the position of the ionization laser with respect to the liquid beam and the delay time of the UV-laser irradiation from the IR-laser irradiation. 

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