@article{TrinhEllisBlandHawthornetal.2013,
  author    = {Trinh, Christopher Q. and Ellis, Simon C. and Bland-Hawthorn, Joss and Lawrence, Jon S. and Horton, Anthony J. and Leon-Saval, Sergio G. and Shortridge, Keith and Bryant, Julia and Case, Scott and Colless, Matthew and Couch, Warrick and Freeman, Kenneth and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Gers, Luke and Glazebrook, Karl and Haynes, Roger and Lee, Steve and O'Byrne, John and Miziarski, Stan and Roth, Martin M. and Schmidt, Brian and Tinney, Christopher G. and Zheng, Jessica},
  title     = {Gnosis - the first instrument to use fiber bragg gratings for OH suppression},
  series = {The astronomical journal},
  volume    = {145},
  journal   = {The astronomical journal},
  number    = {2},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-6256},
  doi       = {10.1088/0004-6256/145/2/51},
  pages     = {13},
  year      = {2013},
  abstract  = {The near-infrared is an important part of the spectrum in astronomy, especially in cosmology because the light from objects in the early universe is redshifted to these wavelengths. However, deep near-infrared observations are extremely difficult to make from ground-based telescopes due to the bright background from the atmosphere. Nearly all of this background comes from the bright and narrow emission lines of atmospheric hydroxyl (OH) molecules. The atmospheric background cannot be easily removed from data because the brightness fluctuates unpredictably on short timescales. The sensitivity of ground-based optical astronomy far exceeds that of near-infrared astronomy because of this long-standing problem. GNOSIS is a prototype astrophotonic instrument that utilizes "OH suppression fibers" consisting of fiber Bragg gratings and photonic lanterns to suppress the 103 brightest atmospheric emission doublets between 1.47 and 1.7 mu m. GNOSIS was commissioned at the 3.9 m Anglo-Australian Telescope with the IRIS2 spectrograph to demonstrate the potential of OH suppression fibers, but may be potentially used with any telescope and spectrograph combination. Unlike previous atmospheric suppression techniques GNOSIS suppresses the lines before dispersion and in a manner that depends purely on wavelength. We present the instrument design and report the results of laboratory and on-sky tests from commissioning. While these tests demonstrated high throughput (approximate to 60\%) and excellent suppression of the skylines by the OH suppression fibers, surprisingly GNOSIS produced no significant reduction in the interline background and the sensitivity of GNOSIS+IRIS2 is about the same as IRIS2. It is unclear whether the lack of reduction in the interline background is due to physical sources or systematic errors as the observations are detector noise dominated. OH suppression fibers could potentially impact ground-based astronomy at the level of adaptive optics or greater. However, until a clear reduction in the interline background and the corresponding increasing in sensitivity is demonstrated optimized OH suppression fibers paired with a fiber-fed spectrograph will at least provide a real benefit at low resolving powers.},
  language  = {en}
}
@article{WolfSanchezYangetal.2019,
  author    = {Wolf, Thomas J. A. and Sanchez, David M. and Yang, J. and Parrish, R. M. and Nunes, J. P. F. and Centurion, M. and Coffee, R. and Cryan, J. P. and G{\"u}hr, Markus and Hegazy, Kareem and Kirrander, Adam and Li, R. K. and Ruddock, J. and Shen, Xiaozhe and Vecchione, T. and Weathersby, S. P. and Weber, Peter M. and Wilkin, K. and Yong, Haiwang and Zheng, Q. and Wang, X. J. and Minitti, Michael P. and Martinez, Todd J.},
  title     = {The photochemical ring-opening of 1,3-cyclohexadiene imaged by ultrafast electron diffraction},
  series = {Nature chemistry},
  volume    = {11},
  journal   = {Nature chemistry},
  number    = {6},
  publisher = {Nature Publ. Group},
  address   = {London},
  issn      = {1755-4330},
  doi       = {10.1038/s41557-019-0252-7},
  pages     = {504 -- 509},
  year      = {2019},
  abstract  = {The ultrafast photoinduced ring-opening of 1,3-cyclohexadiene constitutes a textbook example of electrocyclic reactions in organic chemistry and a model for photobiological reactions in vitamin D synthesis. Although the relaxation from the photoexcited electronic state during the ring-opening has been investigated in numerous studies, the accompanying changes in atomic distance have not been resolved. Here we present a direct and unambiguous observation of the ring-opening reaction path on the femtosecond timescale and subangstrom length scale using megaelectronvolt ultrafast electron diffraction. We followed the carbon-carbon bond dissociation and the structural opening of the 1,3-cyclohexadiene ring by the direct measurement of time-dependent changes in the distribution of interatomic distances. We observed a substantial acceleration of the ring-opening motion after internal conversion to the ground state due to a steepening of the electronic potential gradient towards the product minima. The ring-opening motion transforms into rotation of the terminal ethylene groups in the photoproduct 1,3,5-hexatriene on the subpicosecond timescale.},
  language  = {en}
}