We report what we believe are the first spectroscopic measurements to be made with a room-temperature quantum-cascade distributed-feedback laser. Using wavelength modulation spectroscopy, we detected N(2)O and CH(4) in the chemical fingerprint wavelength range near 8microm . The noise equivalent absorbance for our measurement was 5 parts in 10(5), limited by excess amplitude modulation on the laser output, which corresponds to a 1-Hz bandwidth detection limit of 250 parts N(2)O in 10(9) parts N(2) in a 1-m path length.

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A very simple printed circuit board attached to a single-board microcomputer for low-energy electron diffraction (LEED) intensity measurement is developed. The principle and the block diagram are given. Some preliminary experimental results of I–E curves of Si(111)-(7×7) and V(100)-(2×2) are given. The angular profiles of the integral spot of Si(111)-(7×7) under different primary electron energies are given, from which the instrument response of our LEED gun is calculated.

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