slide1 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Why is this paper interesting? PowerPoint Presentation
Download Presentation
Why is this paper interesting?

Loading in 2 Seconds...

play fullscreen
1 / 9

Why is this paper interesting? - PowerPoint PPT Presentation


  • 125 Views
  • Uploaded on

Why is this paper interesting?. Relevant to the groups active research Water is easily available in all phases -PACER measurements : D₂O/H₂O . Water. Simple Molecule: HOMO, HOMO-1, HOMO-2 all identical p-type orbitals O₂ is not so simplistic. HOMO - 2. HOMO separation;

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Why is this paper interesting?' - lenora


Download Now An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

Why is this paper interesting?

  • Relevant to the groups active research
  • Water is easily available in allphases
  • -PACER measurements : D₂O/H₂O
slide2

Water

  • Simple Molecule: HOMO, HOMO-1,
  • HOMO-2 all identical p-type orbitals
  • O₂ is not so simplistic....

HOMO - 2

  • HOMO separation;
  • compare to CO₂.....

3.7eV

HOMO - 1

2.2eV

HOMO

12.6eV

slide3

HHG in Molecules

  • Electron wavepacket launched – orbital information
  • Propagation in continuum – phase accumulation
  • Dipole amplitudes interfere – phase & amplitude modulation
experiment
Experiment

To date: HHG in H₂O observed using:

  • 1) 800nm light with microdroplets
  • 2) 3.6μm light with liquid

This paper: Results from HHG in gas-phase H₂O

800nm & 1300nm light

Intensities ≥ Isat

Harmonics: 39th at 800nm

91st at 1300nm

MOLECULES ARE NOT ALIGNED FOR THIS PAPER

experimental set up
Experimental Set-Up
  • HHG 800nm light

- Produced: 50cm Semi-Infinite Gas Cell (SIGC)

- SIGC: 150μm pinhole

- Ti:SaphRegen Amp (~3.5mJ, 40fs, 100Hz)

- Focussed: f = 75cm achromatic lens

- 2mm uncoated fused SiO₂ window

Flat field concave grating → MCP →(Phosphor Screen) →CCD

results
Results
  • Note Xe cut-off points
  • Previous H₂O HHG work: Highest photon energy: ~42eV
  • This experiment: ~60eV
  • SIGC HHG efficiency: ~
  • Extension of HHG cut off.....

?

  • (a) Xe: Cut off: 106.8eV ?
  • (a)H2O: Cut off: 107.2eV ?
results1
Results
  • Harmonic spatial profiles nearly Gaussian in shape
  • Not the case beyond H₂O saturation intensity
  • Distortion due to plasma formation?
  • Need good spatial mode: extract harmonic phase and
  • amplitude
  • Higher photon energies & better phase matching –
  • magnify suppression → extension of cut off harmonics
results2
Results
  • Xe and H₂O at 1300nm, I =
  • Cut off energies: ~87eV for H₂O

~60eV for Xe

Extension allows study of electronic and geometric structure – multiorbital and multicentre interferences start to appear in spectra at higher energies

conclusions
Conclusions
  • HHG demonstrated in H₂O: 800nm: ~60eV

1300nm: ~87eV

  • Suppression of ionization shown to be due to orbital symmetry at tunnelling stage – comparing Xe and H₂O harmonics

→Easy to align: study different orbital contribution to HHG

HOMO separation supports this

  • Interesting prospects with H₂O within the QOLS group