Spectroscopy single molecular level

Optofluidic detection techniques based on SERS can be used as a highly sensitive biomedical and chemical sensor. Combining a microfluidic device with Raman spectroscopy provides an opportunity to analyze target molecules in real time without labeling at the single molecular level. There are several methods for combining... 

In fluorescence spectroscopy and optical pumping experiments, the high intensity of lasers allows an appreciable population in selectively excited states to be achieved which may be comparable to that of the absorbing ground states. The small laser linewidth favors the selectivity of optical excitation and results in favorable cases in the exclusive population of single molecular levels. These advantageous conditions allow one to perform absorp-... 

Huang, Y. S., Karashkna, T., Yamamoto, M., and Hamaguchi, H. 2006. Molecular-level investigation of the structure, transformation, and bioactivity of single living flssion yeast cells by time- and space-resolved Raman spectroscopy. Biochemistry. 44 10009-19. 

Fluorescence spectroscopy has sensitivity as high as up to the single-molecular detection level. However, fluorescence detection of has been usually unsuccessful by their... 

Inspired by these Surface Science studies at the gas-solid interface, the field of electrochemical Surface Science ( Surface Electrochemistry ) has developed similar conceptual and experimental approaches to characterize electrochemical surface processes on the molecular level. Single-crystal electrode surfaces inside liquid electrolytes provide electrochemical interfaces of well-controlled structure and composition [2-9]. In addition, novel in situ surface characterization techniques, such as optical spectroscopies, X-ray scattering, and local probe imaging techniques, have become available and helped to understand electrochemical interfaces at the atomic or molecular level [10-18]. Today, Surface electrochemistry represents an important field of research that has recognized the study of chemical bonding at electrochemical interfaces as the basis for an understanding of structure-reactivity relationships and mechanistic reaction pathways. 

The kinetics of the hydrolysis of acetic anhydride in dilute hydrochloric acid, Scheme 1.9, may be described by a single pseudo-first-order rate constant, k, and the investigation by calorimetry combined with IR spectroscopy, as we shall see in Chapter 8, provides a clear distinction between the heat change due to mixing of the acetic anhydride into the aqueous solution and that due to the subsequent hydrolysis. This model of the reaction is sufficient for devising a safe and efficient large-scale process. We know from other evidence, of course, that the reaction at the molecular level is not a single-step process - it involves tetrahedral intermediates - but this does not detract from the validity or usefulness of the model for technical purposes. 

It should be noted that the rotational spectroscopy of CO confined to a single vibrational level, usually the ground v = 0 level, provides only a limited amount of information about molecular structure. In the field of vibration-rotation spectroscopy, however, CO has been studied extensively and particular attention paid to the variation of the rotational and centrifugal distortion constants with vibrational quantum number. Vibrational transitions involving v up to 37 have been studied with high accuracy [78, 79, 80], and the measurements extended to other isotopic species [81] to test the conventional isotopic relationships. CO is, however, an extremely important and widespread molecule in the interstellar medium. CO distribution maps are now commonplace and with the advent of far-inffared telescopes, it is also an important... 

The development of new catalytic materials needs to be complemented with detailed studies of the surface chemistry of catalysis at the molecular level in order to better define the requirements for the catalytic active sites. The wide array of modem spectroscopies available to surface scientists today is ideally suited for this task (see Surfaces). Surface science studies on catalysis typically probe reaction intermediates on model metal samples under well controlled conditions. This kind of study is traditionally carried out in ultrahigh vacuum (UHV) systems such as that shown in Figure 10. Single crystals or other well-defined metal surfaces are cleaned and characterized in situ by physical and chemical means, and then probed using a battery of surface sensitive techniqnes snch as photoelectron (XPS and UPS), electron energy loss (ELS... 

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