P-polarized

The external reflection of infrared radiation can be used to characterize the thickness and orientation of adsorbates on metal surfaces. Buontempo and Rice [153-155] have recently extended this technique to molecules at dielectric surfaces, including Langmuir monolayers at the air-water interface. Analysis of the dichroic ratio, the ratio of reflectivity parallel to the plane of incidence (p-polarization) to that perpendicular to it (.r-polarization) allows evaluation of the molecular orientation in terms of a tilt angle and rotation around the backbone [153]. An example of the p-polarized reflection spectrum for stearyl alcohol is shown in Fig. IV-13. Unfortunately, quantitative analysis of the experimental measurements of the antisymmetric CH2 stretch for heneicosanol [153,155] stearly alcohol [154] and tetracosanoic [156] monolayers is made difflcult by the scatter in the IR peak heights. 

Fig. IV-13. Example of a p-polarized reflection spectrum from Ref. [154] for a stearyl alcohol monolayer on water. The dashed line is the baseline to be subtracted from the spectra. [Reprinted with permission from Joseph T. Buontempo and Stuart A. Rice, J. Chem. Phys. 98(7), 5835-5846 (April 1, 1993). Copyright 1993, American Institute of Physics.]...

Figure Bl.5.8 Random distribution of (a) non-chiral adsorbates that gives rise to a surfaee having effeetive oo m-synnnetry (b) ehiral moleeules that gives rise to effeetive oo-synnnetry. (e) SH intensity versus the angle of an analyser for a raeemie (squares) and a non-raeemie (open eireles) monolayer of ehiral moleeules. The pump beam was p-polarized the SH polarization angles of 0° and 90° eorrespond to s- and p-polarization, respeetively. (From [70].)...

Figure Bl.5.15 SFG spectrum for the water/air interface at 40 °C using the ssp polarization combination (s-, s- and p-polarized sum-frequency signal, visible input and infrared input beams, respectively). The peaks correspond to OH stretching modes. (After [ ].)...

On metals in particular, the dependence of the radiation absorption by surface species on the orientation of the electrical vector can be fiilly exploited by using one of the several polarization techniques developed over the past few decades [27, 28, 29 and 30], The idea behind all those approaches is to acquire the p-to-s polarized light intensity ratio during each single IR interferometer scan since the adsorbate only absorbs the p-polarized component, that spectral ratio provides absorbance infonnation for the surface species exclusively. Polarization-modulation mediods provide the added advantage of being able to discriminate between the signals due to adsorbates and those from gas or liquid molecules. Thanks to this, RAIRS data on species chemisorbed on metals have been successfidly acquired in situ under catalytic conditions [31], and even in electrochemical cells [32]. 

The reflection coefficients rP and r give the electric field in the reflected beam for each polarization. Since the intensity of light is proportional to the square of the electric field, the reflectances for s- and p-polarized... 

Figure Bl.26.12. Plot of the reflectivity of s- and p-polarized light from a material with refractive index n = 3. (C) REFLECTION AT MULTIPLE INTERFACES...

Figure B2.1.6 Femtosecond spectrometer for transient hole-burning spectroscopy with a continuum probe. Symbols used bs, 10% reflecting beamsplitter p, polarizer. The continuum generator consists of a focusing lens, a cell containing flowing water or ethylene glycol or, alternatively, a sapphire crystal and a recollimating lens.

Figure C 1.5.13. Schematic diagram of an experimental set-up for imaging 3D single-molecule orientations. The excitation laser with either s- or p-polarization is reflected from the polymer/water boundary. Molecular fluorescence is imaged through an aberrating thin water layer, collected with an inverted microscope and imaged onto a CCD array. Aberrated and unaberrated emission patterns are observed for z- and xr-orientated molecules, respectively. Reprinted with pennission from Bartko and Dickson [148]. Copyright 1999 American Chemical Society.

Fig. 2. A magnetooptical player (2). P = polarizer MC = magnetic coil (for magnetooptical writing) NBS = neutral beam spHtter PBS = polarizing beam...

P = polarizer (axis Hes ia the page) A = analyzer (axis Hes perpeadicular to the page). 

With p-polarized radiation and incident angles near grazing incidence an increase in sensitivity of approximately a factor of 25 can be achieved in comparison with transmission experiments [4.265]. This advantage is reduced to a factor of 17 for a more realistic experimental situation in which the spread of incident angles is ca. 5° at approximately 85°. 

Fig. 4.54. IR reflection spectra from an ODS monolayer on silicon for s- and p-polarized radiation at different incident angles ft Symmetric (s), asym-...

Fig. 4.55. Experimental and calculated (dashed line) RAIR-spectra for poly(methyl methacrylate) films 3270 + 100 nm, 362 30 nm, and 78 + 15 nm thick (a) p-polarized light incident at 60° (b) s-polarized light incident at 60°, after [4.266].

Debye, P. Polar Molecules" Chemical Catalog Co., 1929. (Dover, New York, reprint.)... 

The occupation number operator for particles of momentum p polarization and antiparticle of momentum q polarization t are given by... 

Figure 5. Effect of the incidence angle on the spectral profile of a transmission coating. G normal incidence. R p-polarization. B s-polarization.

Figure 6. Reflectance for s- and p- polarization of a 8 layers 45° beam splitter.

Figure 7. Reflectance versus semi-angular field for both s- and p- polarization at 510 nm.

Figure 26. Bench for s- and p- polarization measurements of the losses due to birefringence in s- and p- polarization (dex scale). The cross in the left image is due to the mirror support.

Novotny et al. [41] used p-polarized reflection and modulated polarization infrared spectroscopy to examine the conformation of 1 -1,000 nm thick liquid polyperfluoropropy-lene oxide (PPFPO) on various solid surfaces, such as gold, silver, and silica surfaces. They found that the peak frequencies and relative intensities in the vibration spectra from thin polymer films were different from those from the bulk, suggesting that the molecular arrangement in the polymer hlms deviated from the bulk conformation. A two-layer model has been proposed where the hlms are composed of interfacial and bulk layers. The interfacial layer, with a thickness of 1-2 monolayers, has the molecular chains preferentially extended along the surface while the second layer above exhibits a normal bulk polymer conformation. 

Brewster-angle microscopy dispensed with the need for a probe molecule [41,42], Brewster-angle microscopy is based solely on the reflectivity properties of p-polarized light. The reflectance of p-polarized light at the water-air interface vanishes at 53.1° (using refractive indices at 20°C) if the interface is perfectly sharp in reality there is a deep minimum near zero. The presence of a monolayer gives an intervening layer of different re-... 

To determine if the resonance peak is due to self-organization, optical spectra of disorganized nanocrystals (see TEM pattern inset Fig. 8) are recorded under v- and p-polar-ization. Under v-polarization, the optical spectrum obtained at 0 = 60° (Fig. 8A) shows one resonance peak at 2.7 eV. This is attributed to the surface plasmon parallel to the substrate. 

Conversely, under p-polarization (Fig. 8B), a splitting of the optical spectra with increasing 0 is observed One of the peaks is shifted toward high energy compared to that of isolated spherical particles, whereas the second one is at lower energy. 

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