Optical responses

Kobayashi T 1994 Measurement of femtosecond dynamics of nonlinear optical responses Modern Noniinear Optics part 3, ed M Evans and S Kielich Adv. Chem. Rhys. 85 55-104... 

In order to illustrate some of the basic aspects of the nonlinear optical response of materials, we first discuss the anliannonic oscillator model. This treatment may be viewed as the extension of the classical Lorentz model of the response of an atom or molecule to include nonlinear effects. In such models, the medium is treated as a collection of electrons bound about ion cores. Under the influence of the electric field associated with an optical wave, the ion cores move in the direction of the applied field, while the electrons are displaced in the opposite direction. These motions induce an oscillating dipole moment, which then couples back to the radiation fields. Since the ions are significantly more massive than the electrons, their motion is of secondary importance for optical frequencies and is neglected. 

The linear and nonlinear optical responses for this problem are defined by e, 2, e and respectively, as indicated in figure Bl.5.5. In order to detemiine the nonlinear radiation, we need to introduce appropriate pump radiation fields E(m ) and (co2)- If these pump beams are well-collimated, they will give rise to well-collimated radiation emitted tlirough the surface nonlmear response. Because the nonlinear response is present only in a thin layer, phase matching [37] considerations are unimportant and nonlinear emission will be present in both transmitted and reflected directions. 

If we consider the optical response of a molecular monolayer of increasing surface density, the fomi of equation B 1.5.43 is justified in the limit of relatively low density where local-field interactions between the adsorbed species may be neglected. It is difficult to produce any rule for the range of validity of this approximation, as it depends strongly on the system under study, as well as on the desired level of accuracy for the measurement. The relevant corrections, which may be viewed as analogous to the Clausius-Mossotti corrections in linear optics, have been the... 

Luce T A and Bennemann K H 1998 Nonlinear optical response of noble metals determined from first-principles electronic structures and wave functions calculation of transition matrix elements P/rys. Rev. B 58 15 821-6... 

Knickelbein M B and Menezes W J C 1992 Optical response of small niobium clusters Rhys. Rev. Lett. 69 1046 Ceilings B A, Athanassenas K, Lacombe D, Rayner D M and Hackett P A 1994 Optical absorption spectra of AUy,... 

Tamarat P, Lounis B, Bernard J, Orrit M, Kummer S, Kettner R, Mais S and Basche T 1995 Pump-probe experiments with a single molecule ac-Stark effect and nonlinear optical response Phys. Rev. Lett. 75 1514-17... 

In view of this apparent contradictory outcome from the transport and magnetic properties, we were motivated to investigate the dynamics of the charge excitation spectrum by optical methods. In fact, the optical measurement is a powerful contactless experimental tool which should in principle allow to unfold the disagreement between and p(7 since the optical response of a metal... 

We now want to study the consequences of such a model with respect to the optical properties of a composite medium. For such a purpose, we will consider the phenomenological Lorentz-Drude model, based on the classical dispersion theory, in order to describe qualitatively the various components [20]. Therefore, a Drude term defined by the plasma frequency and scattering rate, will describe the optical response of the bulk metal or will define the intrinsic metallic properties (i.e., Zm((a) in Eq.(6)) of the small particles, while a harmonic Lorentz oscillator, defined by the resonance frequency, the damping and the mode strength parameters, will describe the insulating host (i.e., /((0) in Eq.(6)). 

Yoshino and co-workers also reported the optical response of a heterojunclion device comprising a P30T and C60 bilayer [90]. The photoresponse of these devices shows a broad excitation profile ranging from 750 nm into the UV. 

Following the consumption of the probe is much less satisfactory than following the buildup of a product, because the optical response is less sensitive. Also, since the... 

The actual analogue values we need to measure reflectance are given on the next page as 7.8.30. as follows. Note that the optical response curves of the measuring parts, i.e.- the non-linearity of the source and detector, are now corrected in the response of the overall instrument. 

The first part of this paper responds to the first two problems through the calculation of the polarizability of CO (1). In this work, we bring our contribution to the three formal challenges enumerated by Ratner (2) in the special issue of Int. J. Quant. Chem. devoted to the understanding and calculation of the non linear optical response of molecules ... 

Tad)eddine, M. and Flament, J.P. (1999) Analysis of a nonlinear optical response of CN- ions adsorbed on metal electrode tentative interpretation by means of ab initio molecular calculations. Chemical Physics, 240, 39-50. 

Romaniello, P. and de Boeij, P.L. (2005) The role of relativity in the optical response of gold within the time-dependent current-density-fimctional theory. Journal of Chemical Physics, 122, 164303-1-164303-6. 

Figure 6.1 Nonlinear optical responses, (a) Second-order SF generation, the transition probability is enhanced when the IR light is resonant to the transition from the ground state g to a vibrational excited state V. CO is the angular frequency of the vibration, (b) Third-order coherent Raman scheme, the vibrational coherence is generated via impulsive stimulated...

Raman excitation. and I2s are the high-frequency and low-frequency components of the pump light pulse. A probe pulse of frequency 12 interacts with the coherence to present the optical response of the fundamental frequency 12 + C0fsl2. (c) Fourth-order coherent Raman scattering, the optical response of the second harmonic frequency 212 + co 2I2 is modulated by the vibrational coherence. 

To ensure interface-selective detection of the Raman-pumped vibrational coherence, one more incident electric field is required. A fourth-order optical response is thereby generated. The requirement is fulfilled by observing the second harmonic (SH) light generated at the interface, instead of the transmitted fundamental light. 

In order to describe the problems of the nonlinear optical response from biological systems, the question of chirality must be addressed. Linear circular dichroism (CD) has been investigated extensively for biological compounds and a wealth of data are available on... 

Banerjee, A., Harbola, M. K., 1999, Density-Functional-Theory Calculations of the Total Energies, Ionization Potentials and Optical Response Properties with the van Leeuwen-Baerends Potential , Phys. Rev. A, 60, 3599. 

---