Dissociation of multiply charged ICN by Coulomb explosion

The fragmentations of iodine cyanide ions created with 2 to 8 positive charges by photoionization from inner shells with binding energies from 59 eV (I 4d) to ca. 900 eV (I 3p) have been examined by multi-electron and multi-ion coincidence spectroscopy with velocity map imaging ion capability. The charge distributions produced by hole formation in each shell are characterised and systematic effects of the number of charges and of initial charge localisation are found.

Three-dimensional imaging of carbonyl sulfide and ethyl iodide photodissociation using the pixel imaging mass spectrometry camera

The Pixel Imaging Mass Spectrometry (PImMS) camera is used in proof-of-principle three-dimensional imaging experiments on the photodissociation of carbonyl sulfide and ethyl iodide at wavelengths around 230 nm and 245 nm, respectively. Coupling the PImMS camera with DC-sliced velocity-map imaging allows the complete three-dimensional Newton sphere of photofragment ions to be recorded on each laser pump-probe cycle with a timing precision of 12.5 ns, yielding velocity resolutions along the time-of-flight axis of around 6%-9% in the applications presented.

Dynamic stark control of torsional motion by a pair of laser pulses

The torsional motion of a molecule composed of two substituted benzene rings, linked by a single bond, is coherently controlled by a pair of strong (3×10^{13}  W cm^{-2}), nonresonant (800 nm) 200-fs-long laser pulses-both linearly polarized perpendicular to the single-bond axis. If the second pulse is sent at the time when the two benzene rings rotate toward (away from) each other the amplitude of the torsion is strongly enhanced (reduced). The torsional motion persists for more than 150 ps corresponding to approximately 120 torsional oscillations. Our calculations show that the key to control is the strong transient modification of the natural torsional potential by the laser-induced dynamic Stark effect.

Multimass velocity-map imaging with the Pixel Imaging Mass Spectrometry (PImMS) sensor: an ultra-fast event-triggered camera for particle imaging

We present the first multimass velocity-map imaging data acquired using a new ultrafast camera designed for time-resolved particle imaging. The PImMS (Pixel Imaging Mass Spectrometry) sensor allows particle events to be imaged with time resolution as high as 25 ns over data acquisition times of more than 100 μs. In photofragment imaging studies, this allows velocity-map images to be acquired for multiple fragment masses on each time-of-flight cycle. We describe the sensor architecture and present bench-testing data and multimass velocity-map images for photofragments formed in the UV photolysis of two test molecules: Br(2) and N,N-dimethylformamide.