Measurements of Radiant Power and Radiant Energy

Grum, F.

doi:10.1016/b978-0-12-304901-8.50013-7

Radiometry 1979

DOI: 10.1016/b978-0-12-304901-8.50013-7

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Measurements of Radiant Power and Radiant Energy

F. Grum

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1986

1987

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Cited by 2 publications

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“…5 Note that irradiance is the accepted standard nomenclature for the radiant power per unit area. For a definition of the fundamental radiometric quantities see, e.g.,Grum and Becherer (1979) and for a translation of the nomenclature the 'International Lighting Vocabulary'(CIE 1970).…”

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confidence: 99%

The measurement of oscillator strengths

1986

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The methods and techniques currently used to measure oscillator strengths (or, equivalently, f-values and transition probabilities) are reviewed. Both linear and non-linear optical methods are discussed.Following references to critical compilations and bibliographies, the definitions concerning the interaction between an electromagnetic radiation field and a medium (consisting of free atoms, for example) are given: linear and non-linear susceptibilities and radiative constants are introduced. Next, the basic principles of linear methods (dispersion, absorption and emission) and non-linear methods (interaction effects near and off resonance) are explained.Measurement techniques are described in detail. The subjects covered are as follows: introductory remarks on equilibrium, number densities, and relative and absolute oscillator-strength scales; methods based on anomalous dispersion (hook and fringe-shift methods, further interferometric techniques and magneto-rotation); methods based on emission and absorption (the curve of growth, absorption methods yielding absolute and relative $values, and emission methods). We introduce the designation 'Ladenburg method' for a combined method that permits oscillator strengths to be determined without assumptions on plasma state. Subsequently, we discuss the methods based on non-linear interactions (phase-matching in non-linear wave mixing, stimulated Raman scattering, dynamic Stark effect) as well as further methods involving lasers.We emphasise the progress toward more accurate measurements in quantitative spectroscopy and the concomitant new applications. We also point out areas where technological advances concerning light sources, spectrometers and standards, open new opportunities for further, more refined studies in experimental and theoretical atomic and molecular physics.

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The measurement of oscillator strengths

1986

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“…The standard experimental approach to measuring absorption of scattering samples is to place the sample inside an Ulbricht (integrating) sphere (Grum and Becherer 1979), thus collecting all scattered light in addition to transmitted light. Measuring seawater at natural concentrations of chlorophyll inside an integrating sphere calls for extremely high resolution and stability of radiative quantities because of high background absorption by water and dissolved matter.…”

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Quantitative in vivo absorption spectra of phytoplankton: Detrital absorption and comparison with fluorescence excitation spectra1

Maske

Haardt

1987

Limnology & Oceanography

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Spectra1 absorption of phytoplankton from cultures and natural samples was measured on filters with various optical setups including collimated and diffuse irradiation and measurements ofwetted filters within an integrating sphere. In suspensions within an integrating sphere, specific absorption coefficients for laboratory cultures varied by a factor of only two.Measurements on filters yielded values dependent on filter load. Specific absorption coefficients derived from measurements of sample filters were considerably higher than values obtained from suspensions in an integrating sphere due to increased diffuseness of irradiance and to pathlength amplification by filter-particle and particle-particle interactions. Measured absorption of phytoplankton in the blue can be increased greatly by absorption of detritus, evident from absorption spectra of depigmented samples on filter. After subtracting detrital absorption, absorption spectra of phytoplankton are qualitatively similar to the corresponding quantum-corrected fluorescence excitation spectra. The detritus-corrected ratio of absorption at 440 vs. 675 nm shows average values between 1 and 1.5.Comparison with published values shows that specific in vivo absorption coefficients of phytoplankton arc mostly overestimated as a result of the methodology applied. In the blue region of the spectrum, overestimation of phytoplankton absorption in field samples is possible if detrital absorption is neglected.

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Measurements of Radiant Power and Radiant Energy

Cited by 2 publications

References 15 publications

The measurement of oscillator strengths

The measurement of oscillator strengths

Quantitative in vivo absorption spectra of phytoplankton: Detrital absorption and comparison with fluorescence excitation spectra1

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