Metastable N/2P/ atoms in the aurora

peer reviewedAuroral spectra have been obtained in the 3380- to 3560-A region to study the forbidden N I 4S-2P doublet at 3466 A. The forbidden N I 3466 A/N2 Vegard-Kaplan ratio is found to remain constant. This is in agreement with the results of a model calculation showing that the dominant source of N(2P) atoms is dissociative excitation of N2 by fast electrons, and the major quenching agent is atomic oxygen. A value of about 5 x 10 to the 9th/cu cm sec is deduced for the ratio of the N(2P) quantum yield to the atomic oxygen deactivation coefficient

Late-acting self-incompatible system, preferential allogamy and delayed selfing in the heteromorphic invasive populations of <i>Ludwigia grandiflora subsp. hexapetala</i>

International audienc

Absolute optical calibrations using a simple tungsten bulb: Theory

The absolute spectral intensity calibration of optical detectors has always been difficult. In the past, this was only possible using expensive sources, which had been cross-calibrated against national standards. We describe a simple theoretical approach to absolute optical calibrations using any ordinary Tungsten light bulb. A key element of the theory is transforming Tungsten into an equivalent black body radiator. This permits direct application of Stefan- Boltzmann’s and Planck’s formulas of radiation

Absolute optical calibration using a simple tungsten light bulb: Experiment

Absolute spectral intensity calibration of optical detectors has always been difficult. Up to now it was only possible through the use of expensive sources, which are cross-calibrated against national standards. At the 28AM optical meeting, a simple theoretical approach to absolute optical calibrations was described using any ordinary tungsten light bulb [1]. A key element of the theory is transforming tungsten into its equivalent blackbody radiator. This permits direct application of Stefan-Bolzmann’s and Planck’s formulas of radiation. The theory has been tested by comparing three household tungsten light bulbs with a calibrated source at several wavelengths typically used in auroral research. The results of this experiment are most encouraging

Auroral excitation and time variations

peer reviewedaudience: researcher, professiona

Excitation processes and pulsations in the polar aurora

audience: researcher, professiona