Imperial College VUV FT Spectrometer

The Imperial College VUV FTS was adapted from a Chelsea Instruments FT spectrometer based on the design and work of Anne Thorne, and employs a novel magnesium fluoride beamsplitter. More details can be found in Anne Thorne's paper (Download Paper)  . This instrument is the first FTS in the world to go down to 135 nm in the VUV, and holds the world short wavelength record for an instrument of its kind. The instrument parameters are;

  • High resolution, resolving power up to 2 000 000 at 200 nm
  • Wavelength coverage, 135 to 800 nm
  • Portable & compact design.

Bruker IFS 125HR Fourier Transform Spectrometer

The Bruker IFS 125HR is a high-resolution Fourier Transform spectrometer designed for precise spectroscopic measurements across the visible to mid-infrared (mid-IR) spectral range. With a maximum resolving power better than 0.001 cm⁻¹, it enables the accurate characterisation of fine spectral features critical for atomic and molecular data studies.

In the AMSG, the 125HR is a cornerstone of our laboratory instrumentation, supporting high-precision measurements of spectral line positions, intensities, and profiles for astrophysically important atoms and molecules. Its flexible optical layout, combined with a range of interchangeable sources, detectors, and beam splitters, allows for optimised performance across different experimental conditions.

The instrument’s exceptional stability, sensitivity, and spectral resolution make it ideally suited for producing high-quality reference data used in astrophysical modelling, laboratory plasma studies, and atmospheric science. This capability ensures our contributions to spectroscopic databases and theoretical models are underpinned by reliable, state-of-the-art measurements.

Light Sources

The hollow cathode lamp (HCL) is an ideal light source for neutral and singly ionised atomic species. The Imperial College HCL's have accessible, interchangeable cathodes allowing the measurement of metals and many other solid elements.

The Penning Discharge Lamp (PDL) is used for singly and doubly ionised atomic species. As with the HCL the PDL has interchangeable cathodes allowing metals and other solid elements to be observed.

We have both Tungsten (visible to IR) and Deuterium (VUV to visible) intensity calibration lamps. The lamps have been calibrated at the National Physical Libratory, UK and Physikalisch-Technische Bundesanstalt (PTB), Germany. The calibration has a maximum accuracy of 3% at 2s.d. providing relative spectral radiance from 140 to 800nm.

The High Pressure Deuterium (HP D2) lamp provides a line free continuous UV spectrum from 180 to 370nm. As with the Xe arc lamp the HP D2 lamp has applications in UV to VUV molecular absorption measurements.

The Xe arc lamp has a high intensity continuum from 200 to 500nm and is used for molecular absorption measurements, including our current research on low temperature SO2 photoabsorption cross sections.

GEORGINA - A novel band-limited optical filter for the UV and VUV

Better signal-to-noise can be obtained by band limiting spectra, and there is a lack of commercially available narrow band limited filters in the UV and VUV, important spectral regions for our FTS instruments. Georgina was designed and built by Jon Murray and Dick Learner to give an adjustable optical filter in the UV and VUV. It has been employed in our work on sulphur dioxide and chromium. More details are available in a published paper (Download Paper)  .