Time-dependent Wavepackets and Photoionization – CS2

Time-dependent Wavepackets and Photoionization – CS2

Our ongoing work on the calculation of time-dependent wavepackets and observables in photoionization is now collected in an OSF project (DOI: 10.17605/OSF.IO/RJMPD). Aspects of this work have previously been published, but much of the detail and methodology underlying the calculations has remained sitting on our computers. As part of our Open Science Initiative, we’re letting this data go free! Head over to the OSF project “Time-dependent Wavepackets and Photoionization – CS2” for more.

Figure shows TRPADs results (a) Calculated TRPADs (0.7eV) (b), (c) Comparison with expt. TRPADs (discrete times).

Angle-resolved RABBIT: new work and presentation

Angle-resolved RABBIT: new work and presentation

The above image shows simulated velocity map images (left, middle) and angle and time-resolved measurements (right) for angle-resolved RABBIT measurements. In this type of measurement, XUV and IR pulses are combined, and create a set of 1 and 2-photon bands in the photoelectron spectrum. The presence of multiple interfering pathways to each final photoelectron band (energy) results in complex and information rich interferograms, with both angle and time-dependence.

A manuscript detailing this work is currently in preparation, and a recent presentation detailing some aspects of the work can be found on Figshare.

Update 24th March – new manuscript, Angle-resolved RABBIT: theory and numerics, pre-print available.

VIRP chamber spectrometer v2.0

VIRP chamber spectrometer v2.0

A little more progress for our Direct Ion Detection project: the images above and below show some developments of our VIRP chamber (for rapid vacuum instrument prototyping), showing v2.0 of the charged particle spectrometer stack (following a rebuild) with some of the in vacuo wiring attached.  Time-lapse build footage to follow!  This configuration will allow us to perform experiments with direct ion detection, and optimise the methodologies and technologies.

Update: time-lapse build footage is now online.

For further background details, see:
A new detector for mass spectrometry: Direct detection of low energy ions using a multi-pixel photon counter
Edward S. Wilman, Sara H. Gardiner, Andrei Nomerotski, Renato Turchetta, Mark Brouard and Claire Vallance
Rev. Sci. Instrum. 83, 013304 (2012).

Improved direct detection of low-energy ions using a multipixel photon counter coupled with a novel scintillator
Winter, King, Brouard & Vallance
International Journal of Mass Spectrometry, 397–398, 27–31 (2016)

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MPPC test set-up

MPPC test set-up

Some progress for our Direct Ion Detection project: the image above shows the beginnings of a test set-up based around a Hamamatsu MPPC chip, which will be coupled to a scintillator coating to form a complete “direct” ion detection system.  This will then be combined with our VIRP chamber (for rapid vacuum instrument prototyping), allowing us to perform experiments with direct ion detection, and optimise the methodologies and technologies. This is a more refined version of the crude test set-up from a couple of weeks ago!

For further backgournd details, see:
A new detector for mass spectrometry: Direct detection of low energy ions using a multi-pixel photon counter
Edward S. Wilman, Sara H. Gardiner, Andrei Nomerotski, Renato Turchetta, Mark Brouard and Claire Vallance
Rev. Sci. Instrum. 83, 013304 (2012).

Improved direct detection of low-energy ions using a multipixel photon counter coupled with a novel scintillator
Winter, King, Brouard & Vallance
International Journal of Mass Spectrometry, 397–398, 27–31 (2016)

MPPC chips & scintillator coatings

MPPC chips & scintillator coatings

A few images of the in progress testing work for the direct ion detection project.  The images show scintillator coatings, made using the laser dye Exalite 389, and a Hamamatsu MPPC chip to form a complete ion detection system.

 

For further background details, see:
A new detector for mass spectrometry: Direct detection of low energy ions using a multi-pixel photon counter
Edward S. Wilman, Sara H. Gardiner, Andrei Nomerotski, Renato Turchetta, Mark Brouard and Claire Vallance
Rev. Sci. Instrum. 83, 013304 (2012).

Improved direct detection of low-energy ions using a multipixel photon counter coupled with a novel scintillator
Winter, King, Brouard & Vallance
International Journal of Mass Spectrometry, 397–398, 27–31 (2016)

PImMS camera with VUV light

PImMS camera with VUV light

UPDATE April 2017 – Some of this work is now published, and data is also available, see Time-resolved multi-mass ion imaging: femtosecond UV-VUV pump-probe spectroscopy with the PImMS camera for details.

Last week was a busy week, with Prof. Claire Vallance (and two colleagues) visiting to help with technology transfer for our Direct Ion Detection project, based on their previous work in this area. As well as preparing some scintillator coatings, we also had the opportunity to try out another flavour of the new detector technologies they’ve been developing, in the form of the time-resolved PImMS camera. The goal for future detector development is to combine these technologies for a single, on-chip, ion detection solution.

The images below show the camera attached to our velocity-map imaging (VMI) chamber and VUV source.


Vacuum sublimation coatings

Vacuum sublimation coatings

Last week was a busy week, with Prof. Claire Vallance (and two colleagues) visiting to help with technology transfer for our Direct Ion Detection project, based on their previous work in this area. Some scintillator coatings, using the laser dye Exalite 389, were successfully prepared. The video shows this (very basic!) coating technique in action, and the image above shows one of the results, under the microscope. This coating will be combined with a Hamamatsu MPPC chip to form a complete ion detection system.

Vacuum sublimation in progress from femtolab.ca on Vimeo.

For further details, see:
A new detector for mass spectrometry: Direct detection of low energy ions using a multi-pixel photon counter
Edward S. Wilman, Sara H. Gardiner, Andrei Nomerotski, Renato Turchetta, Mark Brouard and Claire Vallance
Rev. Sci. Instrum. 83, 013304 (2012).

Improved direct detection of low-energy ions using a multipixel photon counter coupled with a novel scintillator
Winter, King, Brouard & Vallance
International Journal of Mass Spectrometry, 397–398, 27–31 (2016)

VIRP Chamber: Vacuum Instrument Rapid Prototyping

VIRP Chamber: Vacuum Instrument Rapid Prototyping

The photographs above show our new Vacuum Instrument Rapid Prototyping (VIRP) chamber. The chamber is based around hardware from Kimball Physics (with a company motto that we can all agree with: to advance humankind by doing good physics), which provides a basic construction framework for vacuum instrumentation.

Combined with home-built parts and active components for measurement and control, the VIRP chamber should provide us with a great test-bed for prototyping new instrument designs and testing new detector hardware, as well as provide the full gamut of basic vacuum equipment testing capabilities.

The first configuration for the VIRP chamber consists of a basic Wiley-McLaren time-of-flight (ToF) instrument. This basic ToF mass spectrometer will be used with a femtosecond laser source for the development of new “direct” ion detection technology, in collaboration with our colleagues at the Oxford University (UK), and the PImMS consortuim, starting from their existing work in this area.

For further details, see:
A new detector for mass spectrometry: Direct detection of low energy ions using a multi-pixel photon counter
Edward S. Wilman, Sara H. Gardiner, Andrei Nomerotski, Renato Turchetta, Mark Brouard and Claire Vallance
Rev. Sci. Instrum. 83, 013304 (2012).

Improved direct detection of low-energy ions using a multipixel photon counter coupled with a novel scintillator
Winter, King, Brouard & Vallance
International Journal of Mass Spectrometry, 397–398, 27–31 (2016)

Quantum scattering in NO2 (pt II)

Quantum scattering in NO2 (pt II)

Another brief glimpse at some recent work – scattering calculations for NO2 (pt II – see pt I here)…

no2 orb 12 ionization

 

(top) the molecular-frame photoelectron flux for light-matter interaction for various photon energies (hence various electron energies) for linearly polarized light aligned to the plane of the molecule.

(middle & bottom) the magnitudes & phases of the various partial wave components which make up the continuum electron wavefunction.  There is a lot of information here!

This is just a snippet from an ongoing effort to explore quantum coherence in molecular ionization.

Quantum scattering in NO2

Quantum scattering in NO2

A brief glimpse at some recent work – scattering calculations for NO2.  The figure shows the molecular-frame photoelectron flux for light-matter interaction of various geometries (linearly polarized light), hence scattering into different continua.  The inset shows the ionizing orbital and molecular geometry.

This is just a snippet from an ongoing effort to explore quantum coherence in molecular ionization.