Relativistic Nonlinear Thomson Scattering: Toward Intense Attosecond Pulse

Abstract

Over many millennia of human history, mankind has been interested in how events change in time, namely their dynamics. However, the time resolution of recording individual steps has been limited to direct sensory perception such as the eye’s ability (0.1 sec. or so) to recognize the motion, until 1800 AD when the technical revolution occurred following the industrial revolution. A famous motion picture of a galloping horse by E. Muybridge in 1878 is a good example of the technological development in time-resolved measurement. By this time, the nanosecond time resolution has been achieved; however, it took another century to break the nanosecond barrier as shown in Fig.1. The Advent of a laser has paved ways to ever shorter time resolution: in the 1980’s, the picosecond barrier was broken and the femtosecond science and technology has rapidly progressed in the 1990’s; at the turn of the 21st century, the femtosecond barrier has been broken (Hantschel et al., 2001), opening up the era of attosecond science and technology. The current shortest duration of a pulse achieved is 80 attoseconds around 100 eV of photon energy (Goulielmakis et al., 2008). Femtosecond science and technology have allowed us to explore various ultrafast phenomena in physical (Siders et al., 1999), chemical (Zewail, 2000) and biological (Vos et al., 1999) systems. A great number of ultrafast atomic motions in biology, chemistry, and physics have been investigated with optical probes. In physics, the nature of atomic rearrangements during phase transitions and the relation between amorphous, liquid and crystalline states has been interest (Afonso et al., 1996; Huang et al., 1998). Along with much interest in spintronics during the last decade, efforts have been made to understand spin dynamics in various pure and complex magnetic systems. In chemistry, the real time observation of atomic motions in chemical reactions has been long thought for. Femtosecond optical and IR technology has served this purpose in excellent ways. Femtosecond pulses have pumped molecules to create wavepackets. The observation of the motion of the wavepackets using femtosecond pulse probe or other methods has provided rich information on chemical reactions (Zewail, 2000). The various chemical bonds such as covalent, ionic, dative, metallic, hydrogen and van der Waals bonds have been studied in the varying complexity of molecular systems from diatomics to proteins and DNA. All of