High-accuracy wave-number measurements in molecular iodine.

Absolute wave-number measurements, with an accuracy of 2-11 parts in 10(9), are presented for 27 (127)I(2) hyperfine-structure lines in the range 5763-6563 A. Individual components were resolved by saturation spectroscopy and their wave numbers measured by a comparison with wavelength standards made using a temperature-stabilized Fabry-Perot interferometer. Good consistency is found among the four accepted (127)I(2)wavelength standards.

Detection of individual atoms in helium buffer gas and observation of their real-time motion.

Single atoms are detected and their motion measured for the first time to our knowledge by the fluorescence photon- burst method in the presence of large quantities of buffer gas. A single-clipped digital correlator records the photon burst in real time and displays the atom's transit time across the laser beam. A comparison is made of the special requirements for single-atom detection in vacuum and in a buffer gas.

Noninvasive magnetic detection of cardiac mechanical activity: experiments.

The magnetic susceptibility of the heart and the intracardiac blood is substantially greater than that of the surrounding lung tissue. The periodic redistribution of blood and tissue during the cardiac cycle will thus alter an externally applied magnetic field. These magnetic field changes can be detected by a magnetometer outside the body, and have been termed magnetic susceptibility plethysmography (MSPG) signals.

Measurement of the human magnetic heart vector.

A unipositional lead system has been developed to record the human magnetic heart vector and to permit comparison with the electric heart vector recorded with a conventional Frank lead system. Recordings made in five normal subjects showed a remarkably consistent relation between the electric and magnetic heart vectors. However, the angle between electric heart vector R and T waves was markedly different from the magnetic heart vector R-T angle.

Image orthicon spectrograph with computer control.

A spectrograph using an image orthicon tube for low light level spectroscopy has been constructed. It has been tested for rapid raman spectroscopy and, with computer control, for transient absorption spectra of ions excited to metastable states. The advantages and disadvantages of the instrument are discussed.