Infrared imaging, near field

Brighter, tunable ultrafast light sources would benefit many of the areas discussed in the report, particularly infrared-terahertz (between visible light and radio waves) vibrational and dynamical imaging, near-field scanning optical microscopy (NSOM), and X-ray imaging. 

FIGURE 3.18 Images showing representative data from phase-separated domains of poly(styrene) in a poly(methyl methacrylate) matrix. Left sample topography. Right apertureless infrared scattering near-field optical images of poly(styrene) domains in a poly(methyl methacrylate) film recorded at the frequencies shown. 

A nano-light-source generated on the metallic nano-tip induces a variety of optical phenomena in a nano-volume. Hence, nano-analysis, nano-identification and nanoimaging are achieved by combining the near-field technique with many kinds of spectroscopy. The use of a metallic nano-tip applied to nanoscale spectroscopy, for example, Raman spectroscopy [9], two-photon fluorescence spectroscopy [13] and infrared absorption spectroscopy [14], was reported in 1999. We have incorporated Raman spectroscopy with tip-enhanced near-field microscopy for the direct observation of molecules. In this section, we will give a brief introduction to Raman spectroscopy and demonstrate our experimental nano-Raman spectroscopy and imaging results. Furthermore, we will describe the improvement of spatial resolution... 

Methods of near-field, midfield and ensemble (global) imaging and real-time visualization have been developed for monitoring gas atomization of liquid metals.[327] The primary process sensors and monitors used include high-speed video and infrared imaging systems. The process monitors allowed continuous and detailed observations of the atomization process and enabled measurements of the key parameters necessary for adequate control and optimization of the process. The sensors provided the operators with real-time information on the temperature of nozzle tip, visual characteristics of atomization plume, and gas and metal flow rates. The images can be displayed in real time, offering the potential for more responsive process control. 

Dragnea, B., J. Preusser, W. Schade, S.R. Leone, and W.D. Hinsberg. 1999. Transmission near-field scanning microscope for infrared chemical imaging. J. Appl. Phys. 86 2795-2799. 

This method requires, however, very precise photometric measurements as photometric redshift estimates are quite versatile. Moreover, the redshift estimates depend on the galaxy types, ages, on the environmental effects acting in clusters and on the available photometric bands. For example, near infrared data are necessary to compute efficiently redshifts at z greater than 1 and wide field near infrared imagers (e.g. the future Wircam at CFHT) are not yet available. 

Fourier-Transform Infrared (FTIR) spectroscopy as well as Raman spectroscopy are well established as methods for structural analysis of compounds in solution or when adsorbed to surfaces or in any other state. Analysis of the spectra provides information of qualitative as well as of quantitative nature. Very recent developments, FTIR imaging spectroscopy as well as Raman mapping spectroscopy, provide important information leading to the development of novel materials. If applied under optical near-field conditions, these new technologies combine lateral resolution down to the size of nanoparticles with the high chemical selectivity of a FTIR or Raman spectrum. These techniques now help us obtain information on molecular order and molecular orientation and conformation [1],... 

IR measurements on doped Si and shown that the subsurface mobile carriers can be probed by their response to an IR near-field with a spatial resolution of 30nm [48]. The group of Havenith presented a scanning near-field infrared microscopy (SNIM) system this is an IR s-SNOM set-up based on a continuous-wave optical parametric oscillator (OPO) as an excitation source with a much wider tunability compared to the usually applied CO2 lasers [49]. With this set-up, a subsurface pattern of implanted gallium ions in a topographically fiat silicon wafer was imaged with a lateral resolution of <30 nm. 

The inventions of the scanning tunnelling microscope (STM) [16] and the atomic force microscope (AFM) [17] have allowed sub-micrometre and, at times, atomic-scale spatially-resolved imaging of surfaces. Spatially-resolved temperature measurements using optical systems are diffraction limited by the wavelength of the radiation involved, which is about 5-10 pm for infrared thermography and about 0.5 pm for visible light [18]. The spatial resolution of near-field techniques (such as AFM) is only limited by the active area of the sensor (which in the case of STM may be only a few atoms at the end of a metal wire). 

Infrared (IR) imaging or mapping techniques are meant here as those that potentially can be used for biosensors and their characterization. Far-field and near-field infrared spectroscopy... 

Synchrotron Infrared spectroscopy has witnessed several important applications in Materials Science over the recent years. This chapter is aimed at highlighting the most recent studies that could inspire new studies from readers. Soft matter (in particular polymer science), catalysis and microscopic ellipsometry have achieved important steps forward in their applications recently, while well-established studies in semiconductors and high pressure studies have generated important results and findings. The field is evolving quickly towards new directions, mainly in the production of intense THz beams that are opening new research directions, in time resolved studies, in fast imaging and in near field infrared microscopy. The recent advances are reported in this chapter. 

If infrared absorption or Raman scattering is used as the contrast mechanism, vibrational spectra of samples can be obtained. The combination of the nanoscale spatial resolution of a scanned probe with the chemical specificity of vibrational spectroscopy allows in situ mapping of chemical functional groups with subwavelength spatial resolution. Figure 12 is a shear force image of a thin polystyrene film along with a representative near-field spectrum of the... 

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