Infrared Spectra of Monolayers on Metal Mirrors

Zavar

et al. 2010

J Opt

PMN-PZT nano-powders were prepared by citrate-nitrate gel-combustion technique and optical parameters were obtained by Kramers-Kronig transformation. Organic metals and metal salts precursor were employed in this process. X-ray diffraction shows that increasing the temperature from 500°C to 800°C reduces the pyrochlore unwanted phase in nano-powders so that in 900°C the single phase of perovskite formed. According to the TEM images, the particles size are in the range of 20-30 nm. FTIR spectrum transmittance confirms the perovskite phase of nano-powders. Using FTIR spectra and Kramers-Kroning relationship, the optical constants including the refractive index, extinction coefficients, real and imaginary parts of dielectric function investigated. In addition, we determined plasma frequencies from energy loss functions at 600°C, 700°C, 800°C and 900°C. The increasing calcination temperature makes the significant changes in optical constants.

Section: Resultssupporting

confidence: 67%

The effect of temperature dependences on optical properties of PMN-PZT nano-powders

Zavar

et al. 2010

J Opt

“…This method was developed in the 1960s and has proved to be a particularly powerful research tool for the study of adsorbed layers on metal surfaces. In fact, the success of IRRAS has contributed substantially to the identification of fundamental principles governing the surface chemistry of metals [19,20].…”

Section: Introductionmentioning

confidence: 99%

IR spectroscopy applied to metal oxide surfaces: adsorbate vibrations and beyond

Yang

Wöll

2017

Advances in Physics: X

Metal oxides are among the technologically most important materials. Almost all metals are covered by one oxide layer under ambient conditions. The characterization of oxide surface properties, therefore, is still attracting an increasing amount of attention in surface science. A challenge is provided by the fact that these materials cannot be studied with standard techniques in a straightforward fashion. In this review, we summarize recent results obtained by IRspectroscopy applied in a reflection-geometry to macroscopic oxide monocrystals. These results provide new insights in the adsorption and subsequent reactions and photoreactions of molecules on these highly interesting, very complex class of materials. In addition, the IR-spectroscopy can also be used to probe photophysical properties, e.g. the generation and decay of electron or hole polarons.

“…As one of various kinds of infrared techniques, reflection-absorption infrared (RAIR) spectroscopy is well fit to the characterization of the ultrathin films with thickness of nanometer level. The characteristic 17 of RAIR is that the resultant electric field vector is perpendicular to the metal surface. Therefore, if molecules are adsorbed onto the substrate with a preferred orientation, vibration modes having transition moments perpendicular to the surface will appear with greater intensity than modes having transition moments parallel to the surface.…”

mentioning

confidence: 99%

Orientation Study of Poly(ethylene terephthlate) Ultrathin Films during Crystallization

Zhang

Yan

et al. 2005

Polym J

In recent years there are numerous applications and processes in which ultrathin polymer films (< about 100 nm) can be found. The role of confinement and interface in altering the physical behavior of polymers has also drawn more attention. It has been found that depending on the thickness of ultrathin films, the glass transition temperature, 1-6 crystallization behavior, 7-9 morphology 10,11 and electrical properties, 12 etc. may be altered. In addition, the polymeric systems in ultrathin films usually show preferred orientation different from that of bulks. For example, Frank et al.8,9 disclosed that while the backbones of poly(di-n-hexylsilane) deposited on the quartz are oriented preferentially in the plane of the film, the mean orientation of poly(ethylene oxides) molecules on oxidized silicon substrate is in the surface-normal direction. Moreover, the PEO lamellae showed interesting film thickness dependent morphology and orientation. Similar study of orientation in ultrathin films can also be found in other polymeric systems. [13][14][15][16] Variety kinds of method 8,9,[13][14][15][16] can be used to study the orientation of polymer in the confined geometry. Among them, Fourier transform infrared (FT-IR) spectroscopy is a usefully technique and has great advantage: it can probe directly to such subtle details as intermolecular interactions, localized molecular conformations and orientation. As one of various kinds of infrared techniques, reflection-absorption infrared (RAIR) spectroscopy is well fit to the characterization of the ultrathin films with thickness of nanometer level. The characteristic 17 of RAIR is that the resultant electric field vector is perpendicular to the metal surface. Therefore, if molecules are adsorbed onto the substrate with a preferred orientation, vibration modes having transition moments perpendicular to the surface will appear with greater intensity than modes having transition moments parallel to the surface. So RAIR is especially useful for determining the orientation of adsorbed molecular species. In this work, the orientation of poly(ethylene terephthlate) (PET) in ultrathin films was determined by the combination of RAIR and IR transmission. As a kind of polymer with considerable commercial importance, the property of PET in bulk has been extensively studied. But the corresponding report of its ultrathin film cannot be found by far. The thickness dependence of the orientation during isothermal crystallization was also investigated. EXPERIMENTAL Sample PreparationPET pellets (M w $ 36000{41000 g/mol, M w =M n $ 1:8{2:05) were produced by Changzheng Chemical Industries, Beijing. The PET pellets were dissolved in chloroform-trifluoroacetic acid (9:1 (v/v)). All glass wafers were cleaned by fresh piranha solution (30% H 2 O 2 mixed in 1:5 ratio with concentrated H 2 SO 4 ). The wafers were then rinsed with copious quantities of deionized water, and dried under a warm nitrogen flow. A 20 nm adhesion layer of chromium and 110 nm layer of Au were deposited on the glass wafers ...