The origin and interpretation of the Raman features of amorphous ͑hydrogenated͒ carbon films deposited at room temperature in the region of 1000-1700 cm Ϫ1 is discussed in this paper. Possible interpretations of the linewidths, positions of the ''G'' graphite peak and ''D'' disordered peak, and their intensity ratios are examined using results obtained from magnetron sputtered and magnetic field enhanced plasma deposited films. It is shown that even small ''clusters'' of condensed benzene rings ͑cluster size below 20 Å͒ in carbon films can explain the observed Raman scattering. Besides the care that should be taken in the correct interpretation of Raman results, the utility of Raman scattering in obtaining an estimate of cluster sizes in amorphous ͑hydrogenated͒ carbon films is discussed. Carbon films prepared by magnetron sputtering show two additional Raman features at 1180 and 1490 cm Ϫ1 in addition to the G and D peaks. It is shown that a correlation exists between the 1180 cm Ϫ1 peak and the sp 3 content in the films.

We report on laboratory experiments to shed light on dust charging and transport that have been suggested to explain a variety of unusual phenomena on the surfaces of airless planetary bodies. We have recorded micron‐sized insulating dust particles jumping to several centimeters high with an initial speed of ~0.6 m/s under ultraviolet illumination or exposure to plasmas, resulting in an equivalent height of ~0.11 m on the lunar surface that is comparable to the height of the so‐called lunar horizon glow. Lofted large aggregates and surface mobilization are related to many space observations. We experimentally show that the emission and re‐absorption of photoelectron and/or secondary electron at the walls of microcavities formed between neighboring dust particles below the surface are responsible for generating unexpectedly large negative charges and intense particle‐particle repulsive forces to mobilize and lift off dust particles.

The effect of nitrogen addition on the structural and electronic properties of hydrogenated amorphous carbon ͑a-C:H͒ films has been characterized in terms of its composition, sp 3 bonding fraction, infrared and Raman spectra, optical band gap, conductivity, and paramagnetic defect. The variation of conductivity with nitrogen content suggests that N acts as a weak donor, with the conductivity first decreasing and then increasing as the Fermi level moves up in the band gap. Compensated behavior is found at about 7 at. % N, for the deposition conditions used here, where a number of properties show extreme behavior. The paramagnetic defect density and the Urbach tailwidth are each found to decrease with increasing N content. It is unusual to find alloy additions decreasing disorder in this manner.