报告题目：Ultrafast coherent x-rays from tabletop lasers - a new tool for science and technology

报 告 人：Henry C. Kapteyn，Department of Physics, JILA and NSF ERC in EUV Science and Technology, University of Colorado and NIST

报告时间：11月11日（周一）10：30

报告地点：物理系三楼报告厅

报告摘要：The discovery of x-rays made possible not-only new medical technologies, but also allowed man to “see” at the atomic scale for the first time, revolutionizing our understanding of matter. Efforts to bring x-ray techniques to femtosecond time-scales—the fundamental atomic time scale— have been ongoing for the past ~¼ century, and are now providing new insight into the behavior of matter. Key to this work has been to understand the coherent high-order harmonic generation (HHG) upconversion process. HHG allows for the light from a high-power femtosecond laser to be coherently upconverted from the infrared into the soft x-ray region of the spectrum, with each x-ray photon resulting from the coherent combination of hundreds or even thousands of photons from the driving laser. The resulting femtosecond and attosecond HHG x-ray sources allow us to probe, using a tabletop setup, the fastest charge, spin and energy transport processes. The capabilities of these sources have increased dramatically with our recent demonstration of bright sources with photon energy >1 keV.[1-3] Recent applications include probing the dynamics of the quantum exchange interaction fundamental to magnetic materials;[4-8] the use of coherent HHG light for tabletop nano-imaging with record 22 nm resolution;[9-11] and studies of the physical limits of energy flow at the nanoscale.[12,13]

1. T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Bal？iunas, O. D. Mu？cke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, "Bright Coherent Ultrahigh Harmonics in the keV X-ray Regime from Mid-Infrared Femtosecond Lasers," Science 336(6086), 1287-1291 (2012).

2. T. Popmintchev, M. C. Chen, P. Arpin, M. M. Murnane, and H. C. Kapteyn, "The attosecond nonlinear optics of bright coherent X-ray generation," Nature Photonics 4(12), 822-832 (2010).

3. M. C. Chen, P. Arpin, T. Popmintchev, M. Gerrity, B. Zhang, M. Seaberg, D. Popmintchev, M. M. Murnane, and H. C. Kapteyn, "Bright, Coherent, Ultrafast Soft X-Ray Harmonics Spanning the Water Window from a Tabletop Light Source," Physical Review Letters 105(17), 173901 (2010).

4. E. Turgut, C. La-o-vorakiat, J. M. Shaw, P. Grychtol, H. T. Nembach, D. Rudolf, R. Adam, M. Aeschlimann, C. M. Schneider, T. J. Silva, M. M. Murnane, H. C. Kapteyn, and S. Mathias, "Controlling the Competition between Optically Induced Ultrafast Spin-Flip Scattering and Spin Transport in Magnetic Multilayers," Physical Review Letters 110(19), 197201 (2013).

5. D. Rudolf, C. La-O-Vorakiat, M. Battiato, R. Adam, J. M. Shaw, E. Turgut, P. Maldonado, S. Mathias, P. Grychtol, H. T. Nembach, T. J. Silva, M. Aeschlimann, H. C. Kapteyn, M. M. Murnane, C. M. Schneider, and P. M. Oppeneer, "Ultrafast magnetization enhancement in metallic multilayers driven by superdiffusive spin current," Nature Communications 3, 1037 (2012).

6. C. La-O-Vorakiat, E. Turgut, C. A. Teale, H. C. Kapteyn, M. M. Murnane, S. Mathias, M. Aeschlimann, C. M. Schneider, J. M. Shaw, H. T. Nembach, and T. J. Silva, "Ultrafast Demagnetization Measurements Using Extreme Ultraviolet Light: Comparison of Electronic and Magnetic Contributions," Physical Review X 2(1), 011005 (2012).

7. C. La-O-Vorakiat, M. Siemens, M. M. Murnane, H. C. Kapteyn, S. Mathias, M. Aeschlimann, P. Grychtol, R. Adam, C. M. Schneider, J. M. Shaw, H. Nembach, and T. J. Silva, "Ultrafast Demagnetization Dynamics at the M Edges of Magnetic Elements Observed Using a Tabletop High-Harmonic Soft X-Ray Source," Physical Review Letters 103(25), 257402/257401-257404 (2009).

8. S. Mathias, C. La-O-Vorakiat, P. Grychtol, P. Granitzka, E. Turgut, J. Shaw, R. Adam, H. Nembach, M. Siemens, S. Eich, C. M. Schneider, T. J. Silva, M. Aeschlimann, M. M. Murnane, and H. C. Kapteyn, "Probing the timescale of the exchange interaction in a ferromagnetic alloy," PNAS 109, 4792 (2012).

9. B. Zhang, M. D. Seaberg, D. E. Adams, D. F. Gardner, E. R. Shanblatt, J. M. Shaw, W. Chao, E. M. Gullikson, F. Salmassi, H. C. Kapteyn, and M. M. Murnane, "Full field tabletop EUV coherent diffractive imaging in a transmission geometry," Optics Express 21(19), 21970-21980 (2013).

10. M. D. Seaberg, D. E. Adams, E. L. Townsend, D. A. Raymondson, W. F. Schlotter, Y. W. Liu, C. S. Menoni, L. Rong, C. C. Chen, J. W. Miao, H. C. Kapteyn, and M. M. Murnane, "Ultrahigh 22 nm resolution coherent diffractive imaging using a desktop 13 nm high harmonic source," Optics Express 19(23), 22470-22479 (2011).

11. R. L. Sandberg, C. Y. Song, P. W. Wachulak, D. A. Raymondson, A. Paul, B. Amirbekian, E. Lee, A. E. Sakdinawat, C. La-O-Vorakiat, M. C. Marconi, C. S. Menoni, M. M. Murnane, J. J. Rocca, H. C. Kapteyn, and J. W. Miao, "High numerical aperture tabletop soft x-ray diffraction microscopy with 70-nm resolution," Proceedings of the National Academy of Sciences of the United States of America 105(1), 24-27 (2008).

12. D. Nardi, M. Travagliati, M. E. Siemens, Q. Li, M. M. Murnane, H. C. Kapteyn, G. Ferrini, F. Parmigiani, and F. Banfi, "Probing Thermomechanics at the Nanoscale: Impulsively Excited Pseudosurface Acoustic Waves in Hypersonic Phononic Crystals," Nano Letters 11(10), 4126-4133 (2011).

13. M. E. Siemens, Q. Li, R. G. Yang, K. A. Nelson, E. H. Anderson, M. M. Murnane, and H. C. Kapteyn, "Quasi-ballistic thermal transport from nanoscale interfaces observed using ultrafast coherent soft X-ray beams," Nature Materials 9(1), 26-30 (2010).