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Atomic, Molecular and Optical Physics

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Full-Text Articles in Physics

Imaging Of Alignment And Structural Changes Of Carbon Disulfide Molecules Using Ultrafast Electron Diffraction, Jie Yang, Joshua Beck, Cornelis J. Uiterwaal, Martin Centurion Sep 2015

Imaging Of Alignment And Structural Changes Of Carbon Disulfide Molecules Using Ultrafast Electron Diffraction, Jie Yang, Joshua Beck, Cornelis J. Uiterwaal, Martin Centurion

Martin Centurion Publications

Imaging the structure of molecules in transient-excited states remains a challenge due to the extreme requirements for spatial and temporal resolution. Ultrafast electron diffraction from aligned molecules provides atomic resolution and allows for the retrieval of structural information without the need to rely on theoretical models. Here we use ultrafast electron diffraction from aligned molecules and femtosecond laser mass spectrometry to investigate the dynamics in carbon disulfide following the interaction with an intense femtosecond laser pulse. We observe that the degree of alignment reaches an upper limit at laser intensities below the ionization threshold, and find evidence of structural deformation, …


Orientation Of Optically Trapped Nonspherical Birefringent Particles, Wolfgang Singer, Timo A. Nieminen, Ursula J. Gibson, Norman R. Heckenberg Feb 2006

Orientation Of Optically Trapped Nonspherical Birefringent Particles, Wolfgang Singer, Timo A. Nieminen, Ursula J. Gibson, Norman R. Heckenberg

Dartmouth Scholarship

While the alignment and rotation of microparticles in optical traps have received increased attention recently, one of the earliest examples has been almost totally neglected—the alignment of particles relative to the beam axis, as opposed to about the beam axis. However, since the alignment torques determine how particles align in a trap, they are directly relevant to practical applications. Lysozyme crystals are an ideal model system to study factors determining the orientation of nonspherical birefringent particles in a trap. Both their size and their aspect ratio can be controlled by the growth parameters, and their regular shape makes computational modeling …