Performance of the vacuum ultraviolet high-resolution and high-flux beamline for chemical dynamics studies at the Advanced Light Source

Abstract

At the Advanced Light Source an undulator beamline, with an energy range from 6 to 30 eV, has been constructed for chemical dynamics experiments. The higher harmonics of the undulator are suppressed by a novel, windowless gas filter. In one branchline high-flux, 2% bandwidth radiation is directed toward an end station for photodissociation and crossed molecular-beam experiments. A photon flux of 10 16 photon/s has been measured at this end station. In a second branchline a 6.65 m off-plane Eagle monochromator delivers narrow bandwidth radiation to an end station for photoionoization studies. At this second end station a peak flux of 3 ϫ 10 11 was observed for 25 000 resolving power. This monochromator has achieved a resolving power of 70 000 using a 4800 grooves/mm grating, one of the highest resolving powers obtained by a vacuum ultraviolet monochromator.

Formation of nitrogenated organic aerosols in the Titan upper atmosphere

“…At wavelengths shorter than 80 nm irradiation, approximately 3-5% of total N 2 molecules experience dissociation. At wavelengths shorter than 66 nm, where the N 2 molecule experiences continuum photoabsorption (23), the photon flux is equal to the N 2 dissociation rates under our optically thick condition and is estimated to be 1-1.5× 10 16 photons∕s, which is consistent with previous measurement (24).…”

Photoionization Dynamics in Pure Helium Droplets

“…16 A schematic of the instrument is shown in Figure 1. Most of the experimental apparatus has been described in detail elsewhere.…”

Photoionization and Photofragmentation of SF6in Helium Nanodroplets

“…At the Chemical Dynamics Beamline, an undulator provides ∼10 16 photons s -1 (2.5% bandwidth) of linearly polarized light from 7 to 30 eV. 31 Terminal 3 consists of a 3m off-plane Eagle monochromator fitted with a 600 lines/mm grating and a best possible energy resolution (E/∆E) ≈ 3000. For these experiments, an Ir-coated master grating blazed for 16 eV was used, and the monochromator was set to provide E/∆E ≈ 600, yielding 10 13 photons s -1 in the range of 20-26 eV.…”