**Seeing Invisible**

476 Laser Pulses – Theory, Technology, and Applications

2007.

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[5] V.V. Apollonov, "Oil films elimination by laser", Оboronzakaz, №17, December, p. 33,

[6] V.V. Apollonov, Yu, S. Vagin, V.V. Kijko, "High rep.rate P-P lasers", Patent RF №

**Chapter 15** 

© 2012 Zhang et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2012 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

**Single-Molecule Recognition and Dynamics** 

Guofeng Zhang, Ruiyun Chen, Yan Gao, Liantuan Xiao and Suotang Jia

Single-molecule spectroscopy has evolved from a specialized variety of optical spectroscopy into a versatile tool used to address a broad range of questions in physics, chemistry, biology, and materials science. Due to the ultra short time duration, the pulsed laser can be applied widely in the research of single-molecule dynamics. In the chapter, we will discuss the laser pulse application in two aspects of single-molecule detection and spectroscopy: fast recognition of single molecules, and manipulation of interfacial electron transfer dynamics.

The chapter is organized as follows. In the part of fast recognition of single molecules, we will discuss the Mandel's Q-parameter of single-event photon statistics for single-molecule fluorescence, recognition of single molecules using Q parameter, and the influence of signalto-background ratio and the error estimates for fast recognition of single molecules. In the other part of the chapter, we will discuss the manipulation of interfacial electron transfer dynamics. First, we will introduce the principle of fluorescence lifetime measurement. Next, we will show the experiment results of the single-molecule and the ensemble under the external electric currents. Last, we will present our analysis and discussion for the results.

Although people most often think about and model molecule systems in terms of individuals, experimental science has been dominated by measurements that result in ensemble averages. This has traditionally hidden much of the rich variety present at microscopic scales. Although detecting single molecules optically was an old dream, the first convincing detection of a single molecule was achieved in 1989 by Moerner and Kador in an absorption measurement (Moerner et al., 1989). Optical spectroscopy offers a wealth of information on the structure, interaction, and dynamics of molecule species. Soon here after, fluorescence was shown to

and reproduction in any medium, provided the original work is properly cited.

**with Pulsed Laser Excitation** 

Additional information is available at the end of the chapter

**2. Fast recognition of single molecules** 

http://dx.doi.org/10.5772/48688

**1. Introduction** 
