A pulsed gas electron diffraction apparatus was developed and applied to investigate an alignment process of molecules in intense laser fields. A two-dimensional ͑2D͒ electron diffraction pattern of jet-cooled CS 2 in intense nanosecond laser fields ͑1064 nm, ϳ0.64 TW/cm 2 , 10 ns͒ was measured using short-pulsed 25 keV electron beam packets ͑ϳ7 ns͒ generated by irradiating a tantalum photocathode with the 4th harmonics of pulsed YAG laser light. The observed anisotropic 2D diffraction pattern was analyzed quantitatively by taking into account the spatio-temporal distributions of the laser pulses, the electron beam packets, and the molecular beam through a numerical simulation of the observed diffraction pattern. The anisotropy of the spatial distribution of molecular axes of CS 2 in the laser polarization direction is accounted for by the effect of the intense laser fields. Considering the spatio-temporal averaging effect, the temporal pulse width of an electron packet required for real-time probing of the alignment process of molecules in intense nanosecond laser fields is discussed. A numerical simulation of temporal and spatial profiles of an electron packet is also performed to examine conditions for generating sub-picosecond ultrashort electron pulse for real-time probing of ultrafast molecular dynamics by the pulsed gas electron diffraction method.

In situ observation of field emissions from an individual carbon nanotube (CNT) was performed by Lorenz microscopy. A bright spot appeared by Lorenz microscopy at the end of the CNT tip during field emission. The bright spot is assumed to be related to the emission site on the CNT. A drastic fluctuation was observed in the emission current above a few tens of microamperes, which was closely related to structural changes at the tip of the CNT. The layers of the CNT were peeled off and they worked as a second emission site by concentration of the electric field.

Emission sites were observed as bright spots near the tip end of a multiwalled carbon nanotube (MWNT) by means of Lorenz microscopy. The bright spots appeared above electric fields as electrons were emitted. A marked fluctuation was observed in the emission current above 20–30 µA, which was closely related to structural changes at the tip of the MWNT. The layers of the MWNT were peeled off during field emission and they functioned as the second emission sites for the concentration of electric field.

Because of rapidly decreasing line-width of integrated circuits, it is necessary to measure and control their critical dimensions with high accuracy. Hitachi has developed a new critical-dimension-measurement scanning electron microscope (CD-SEM) S-90(X) series, which has a new electron optics with retarding and boosting electric fields. The upper pole piece of the objective lens is kept at a high positive voltage with respect to the ground so as to reduce aberration of the objective lens drastically. To optimize the boosting voltage we have developed optics simulators that is capable of computing aberration coefficients in electric and magnetic mixed fields. At the optimized boosting voltage of around 5kV. 3nm resolution is achieved for a final accelerating voltage of 8(X)V. The high boosting voltage is effective in imaging bottoms of contact holes having high aspect ratios.

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