Photo-absorption cross section

Particle-in-cell simulation, 154 Phonon stiffening, 36 Phonon-magnon coupled mode, 39 Photo-absorption cross section, 156 Photo-induced phase transitions, 42 Photo-nuclear activation, 173 PIC, 135... 

For comparison with experimental data [100-102], it is common to evaluate the oscillator strengths, photo absorption cross section and EELS (Electron Energy Loss Spectrum) defined here in terms of the imaginary part of the polarizability 7 ... 

In analogy to (15.3.25) and (15.3.26) the functions Gi 2 can be related to the off-shell photo-absorption cross-sections with polarized photons and nucleons. There are four independent amphtudes, specified by the helicities of the virtual photon and nucleon the rest are related to these by parity and time-reversal invariance. Conventionally the four transitions are labelled by the total Jz involved and a label L or T to indicate a longitudinal photon (A, = 0) or a transverse photon (A-y = -1-1). The following is the pattern of transitions ... 

In the last expression 5n r,cu) stands for the Fourier transform of n r,t) — n r), where n r) is the ground-state density of the system. The quantity that is usually measured in experiments, the photo-absorption cross-section, is essentially proportional to the imaginary part of the djmamical polarizability averaged over the three spatial directions... 

Fig. 4.3. Total photo-absorption cross-section of xenon versus photon energy in the vicinity of the 4d threshold. The solid hne represents TDDFT calculations and the crosses are the experimental results of [43]. Figure adapted from [42]...

Gradients of molecular properties. The total photo-absorption cross section is maximized with respect to the participation coefficients by using standard optimization techniques (e.g., the quasi-Newton BEGS algorithm). The gradients of the photo-absorption probability are computed using the finite increment expression. 

Given that the absorption cross-section of 07+ at the photo-ionization threshold is 10-19 cm2 and that the oxygen abundance is 10-2 by mass, find the bound-free opacity (cm2 gm-1) due to oxygen at that frequency, and compare it to the electron scattering opacity. 

Equation (8) therefore allows us to use directly tabulated subshell photo-ionization cross sections (p) instead of mass absorption coefficients (a). F is the integrated photoelectron signal from an appropriate subshell of the monolayer adatom Yg the integrated signal from the relevant subshell of the substrate which is not simply the area of the core-level peak p and p. 

Classical absorption and photo dissociation cross sections... 

The absorption cross sections for NO2 and the corresponding quantum yields are given in Table 8 and 9, respectively. The photolysis of NO2 has been investigated intensively over the last 40 years because of its critical role in the formation of ozone in the polluted tropospheric boundary layer [56-63]. The three reactions of Eqs. 33 and 34 form the basis for the photochemical production of ozone. If one considers only these three reactions, then the photo-stationary state (or photochemical steady-state approximation) can be invoked around the oxygen atom as follows ... 

The absorption cross sections of CIONO2 (Figure 4.50) have been measured by Molina and Molina (1979) and by Burkholder et al. (1994). The values are in good agreement and exhibit a temperature variation. The nature of the photo-fragments has been investigated in several laboratory studies. As concluded by JPL (1997), the quantum efficiency i for the following channel... 

Notes. Key parameters for consideration of the photolysis of iodine-containing gases in the air (data taken from the International Union of Pure and Applied Chemistry (lUPAC) Subcommittee for Gas Kinetic Data Evaluation online database http //www.iupac-kinetic.ch.cam.ac.uk/). a Photo-dissociation threshold wavelength, b Bond dissociation energy (298 K). c Wavelength of maximum absorption, d Peak molecular absorption cross-section (298 K). 

The integrated photonuclear cross section. The total integrated photo-nuclear cross section is an important quantity for it demonstrates that the giant resonance is caused, in the main, by absorption of electric dipole radiation. The total integrated cross section has been calculated by Levinger and Bethe. For electric dipole radiation, the cross section for absorption for a particular... 

---