Probe radiation

Ayy = (6.0 5.5) T, and A22 = (16.9 2.5) T (conventional dashed Unes). This again demonstrates the sensitivity of NFS for hyperfine interactions in nuclear ( Fe) scatterers. There can be no doubt that NFS benefits from experimental conditions such as polarization and time structure, and also from a beam diameter in the submillimeter range of the probing radiation. 

The IR probe radiation, provided by a liquid N2-cooled line-tunable CO laser, is passed through the cell collinearly or almost collinearly with the uv photolysis radiation. The probe beam is then directed onto an IR detector using a filter for either selectively blocking the photolysis beam or... 

Now that the parameters of typical prototype systems have been considered, it seems worthwhile to consider further variations that could be used to enhance the power and/or versatility of the basic apparatus. An obvious improvement would be to use a completely tunable IR probe source. As mentioned above, a globar source is completely tunable but with a lower than desired number of photons per unit bandwidth (60,73). There are a number of other means of producing completely tunable IR probe radiation with enough intensity to pull the detector out of the blackbody-noise regime. 

Nevertheless, we were able to develop a transient absorption apparatus involving IR probe radiation that is suitable for gas phase studies, as have a number of other groups either coincident with or subsequent to our work [1]. In the remainder of this article we will discuss the apparatus and the results of our studies on three prototypical metal carbonyl species Fe(C0>5, Cr(C0>5 and Mn2(CO)] o The discussion in this article will center on the nature of the photolytically generated coordinatively unsaturated species, their kinetic behavior and photophysical information regarding these species. This latter information has enabled us to comment on the mechanism for photodissociation in these systems. Since most of the results that will be discussed have been presented elsewhere [3-10], we will concentrate on a presentation of data that illustrates the most important features that have come out of our research and directly related research regarding the kinetics, photophysics and photochemistry of coordinatively unsaturated metal carbonyls. 

Stettbacher(Ref 2 Ref 8,p 361) proposed a test which was claimed to det simultaneously brisance and energy. In this method, known as Strahlungs probe (Radiation Test), a finely powdered expl (ca 50g), packed lightly in a thick Fe or Ni crucible, was placed in the center of a square plate of soft Fe, 6.8mm thick, supported on the op of a hollow cylinder. After initiating the expl Dy means of l-2g MF-LA mixt, the detonating effect was measured by the depth of impression... 

Du, Y., Wu, J., Li, F., Liu, A. 1999. A pulse radiolysis study on energy transfer mechanism in trioctylphosphineoxide-cyclohexane and tributylphosphate-cyclohexane systems by using benzophenone as a probe. Radiat. Phys. Chem. 54 455 161. 

Attenuated total reflection FTIR is a well-established technique for obtaining absorbance spectra of opaque samples. The mode of interaction is unique because the probing radiation is propagated in a high index-of-refraction internal reflection element (IRE). The radiation interacts with the material of interest, which is in close contact with the IRE, forming an interface across which a nonpropagating evanescent field penetrates the surface of the material of interest to a depth in the order of one wavelength of the radiation. The electric field at the interface penetrates the rarer medium in the form of an evanescent field whose amplitude decays exponentially with distance into the rarer medium. 

No. Technique name Probing radiation Main nuclear reaction Detected radiation Sources Primary/secondary detected elements... 

In aqueous solutions, the situation is clarified by the solvent. This solvent keeps the complex ions apart at mean distances, defines them as independent stable entities, and permits probing radiation (e.g., visible light) to pick them out from the surroundings (Fig. 5.5). 

What about the determination of voids in a liquid Determination of the short-range order may not allow one to determine the distribution (number and size) of fluctuating voids in the liquid." While such voids may play a vital part in the mechanism of transport, they are voids and hence would hardly make much impression upon the probing radiation. 

Inverse Raman scattering Inverse Raman scattering (IRS) is a coherent process involving stimulated loss at an anti-Stokes-shifted frequency. The term inverse Raman refers to the fact that, at resonance, the probe radiation is attenuated. In spontaneous Raman spectroscopy, on the other hand radiation at Raman-active frequencies would he generated in the course of the experiment. Inverse Raman scattering (IRS) and stimulated Raman gain (SRG) are closely related. While one involves stimulated gain at an anti-Stokes-shifted frequency, the other involves stimulated loss at a Stokes-shifted frequency. 

One of the most significant implications of the result is that an absorption spectrum measured with intense white light may be significantly different from the spectrum that would be observed using tunable monochromatic radiation. In particular, there should be a decrease in the apparent width of many lines in any absorption spectrum measured with broadband radiation. This is because, for any sample transition of frequency coq, photons of appreciably off-resonant frequency (oiq + fi) can be cooperatively absorbed and result in the excitation of two separate molecules, provided selection rules permit. In fact the Lorentzian linewidth of the concerted absorption process is readily shown to be approximately 0.64 x the ordinary absorption linewidth, if the probe radiation is assumed to be of nearly constant intensity in the frequency region of interest. Nonetheless, the observed linewidth would not be reduced to quite this extent, because of the additional and invariably stronger response associated with normal single-photon absorption. 

For low intensities of probing radiation, the absorption coefficient is independent of intensity but for large intensities, the absorption decreases because of saturation effects (discussed later in the chapter). 

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