Trapping blackbody

The sample is surrounded by a water-cooled blackbody (called the trapping blackbody) in order to reduce the emission from within the vicinity of the sample. The reflection from the surface of the sample is also absorbed by this trapping blackbody. 

Even if the temperature of the trapping blackbody is lowered, the varying background emission cannot be removed when the temperature of the sample is low. In such a case, if the temperature and emittance of the trapping blackbody is known, the varying background emission can be removed by the following calculations. 

The intensity of emission from the sample 7s(v, T) obtained by the method described above can be expressed by the following equation, where the reflectance of the sample is denoted by r v, T) and the intensity of emission from the trapping blackbody by /xb(v) (the temperature of the trapping blackbody is kept constant in all the measurements conducted... 

Figure 15.8 Emission spectra of a polystyrene film at 30°C. (a) Spectrum before the correction for the emission from the trapping blackbody and (b) spectrum after the correction for the emission from the trapping blackbody. See text for details.

As an example similar to that described, the measurement of emission from a 30 pm-thick polystyrene film on a gold-deposited mirror is described. The temperatures of reference blackbodies 1 and 2 were 40.8 and 80 °C, respectively. The emission from the gold-deposited mirror itself is so weak that it may be disregarded in the present measurement. However, the emission from the trapping blackbody, which passes through the sample and is reflected back by the gold-deposited mirror, overlaps the emission from the sample. The trapping blackbody used in this measurement has an emittance of... 

At still lower temperatures little of the emission is in the visible, but the effects of blackbody radiation can still be very important. The Sun s light warms the Earth to a mean temperature of approximately 290K the Earth, in turn, radiates energy out into space. For the Earth kmax 10 // m, far out in the infrared. If this radiation is trapped... 

Blackbody-Induced Radiative Dissociation (BIRD) In this technique also, ion dissociation occurs by absorption of IR photons but without the use of lasers [22], Instead, the trapped ions are activated by absorption of blackbody... 

Hoekstra S, Gilij anise J, Sartakov B, Vanhaecke N, Scharfenberg L, van de Meerakker S, Meijer G. (2007) Optical pumping of trapped neutral molecules by blackbody radiation. Phy.s. Rev. Lett. 98 133001/1-4. 

In the technique called blackbody infrared radiation dissociation (BIRD), developed in E.R. Williams laboratory, ions trapped in an ICR cell at very low pressure absorb infrared photons emitted by the cell walls. Dissociation decays in the second to minute time frame can be followed. In both techniques, the analysis of the temperature dependence of the rate constant leads to activation parameters. BIRD has been applied to biologically important non-covalent complexes like proton-bound dimers of amino acids or double-stranded DNA complexes. 

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