Generation of Light by the Relative Motion of Contiguous Surfaces of Mercury and Glass

Abstract

Balls of ultraviolet-transmitting glass containing liquid mercury, the vapor of mercury, and helium at various pressures have been spun over a wide range of rotation rates to generate light at 23°C. For the angular velocities employed, the pool of mercury exhibited no linear motion. In the case of a given ball, light was found to be emitted in a continuous discharge and sometimes in pulses of full width at halfmaximum 5 jusec as well. When the ball moves, the discharges occur between the liquid mercury and electrons trapped in surface states on the surface of the glass. The discharges assume more than one form, and their properties have been studied as a function of the rotation rate. Spectrograms of the emitted light have been observed in a quartz spectrograph. Lines have been assigned to Hg, He i, He n, C I, C n, CO, CO + , CO2, C02 + , H, Si, and B. The atomic spectral lines of Si and B are emitted from neutral atoms residing on the surface of the glass and loosely bound. In the presence of concentrated electronic surface charge, the photographed lines of Si and B exhibit a displacement to the red. The intensity of emission was noted to decrease gradually over a long period of continuous rotation of the ball.

Triboluminescence and Triboelectrification by the Motion of Mercury Over Glass Coated with Scintillator Dyes

“…While many details of the basic mechanism remain obscure, the process involves charge separation at the mercuryglass interface with the subsequent charge recombination reaction being energetic enough (>20 eV) to pro-duce excited states of the inert gases, mercury and even of the silicon and boron of the glass, and to cause decomposition of such molecules as methane. We report here that coating the glass surface with a scintillator compound results in intense luminescence that is color-specific to the coating during movement of mercury over the surface and that this light emission is localized at the scintillator coating and does not extend into the interior volume as has been reported when only mercury and glass are involved (6). Other significant differences that can be attributed to the scintillator coating and potential difference measurements are also discussed.…”

“…While a detailed mechanism of the phenomenon can obviously not be presented on the basis of the experiments here, these results combined with previous studies of static electrification and solid-state luminescent processes allow some possible schemes to be presented. The process of contacting mercury with glass causes the mercury to become positively charged and the glass negatively charged as a result of electrons from the mercury moving into unfilled surface states of the glass (6). The separation of the mercury and glass surfaces initiates a discharge, and based on the fact that emission from He has been observed under these conditions as well as decomposition methane and other hydrocarbons, the excitation energy produced by this discharge is greater than 20 eV (7).…”

“…The explanation that is in general agreement with present thinking, namely, that a static electric charge builds up, was first put forth by Huksbee (2) in 1705. Recent workers in this field have observed chemical reactions in a triboelectric discharge (3,4) and have studied the spectra of light generated by the relative motion of contiguous surfaces of mercury and glass (5)(6)(7). In related experiments, contact electrification potentials as high as 100V have been measured (8).…”

Gaseous reactions and luminescence initiated by triboelectricity

“…Earlier spectroscopic studies (2,5) have shown the presence of He and Ar lines in the luminescence spectra of He and Ar filled luminescence tubes. In order to produce emission from He an excitation energy in excess of 20 eV is required.…”