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Probe material and molecular properties with unprecedented flexibility on ultrafast time scales

KMLabs Y-Fi™ VUV provides bright femtosecond pulses at numerous wavelengths across the vacuum ultraviolet (VUV) region, from 6.0 eV (205 nm) to 10.8 eV (115 nm). The discrete tunability of the KMLabs Y-Fi VUV vacuum ultraviolet source enables researchers to study a wide range of materials and materials properties. A simple computer-selected change of photon energy provides a powerful capability, previously only available at a synchrotron; this ability to easily change the laser wavelength can enhance many experiments. For example, in angle-resolved photoemission (ARPES) experiments, this tunability allows researchers to distinguish surface effects from bulk effects. For time-of-flight (ToF) studies of molecules, the tunability can distinguish otherwise identical isomers.

Y-Fi VUV is also highly focusable, and the appropriate optics can be used to reach spot sizes below 10 microns. This ability will allow researchers to examine new types of samples, including materials that are polycrystalline, spatially inhomogeneous, faceted, or simply very small.

Y-Fi VUV produces pulses with durations below 250 femtoseconds, enabling scientists to probe ultrafast dynamics of molecules and materials. The 1 MHz repetition rate enables rapid data collection and avoids space-charge effects.

Additionally, Y-Fi VUV is “application ready,” including the appropriate focusing and beam-steering elements to enable fast integration with experimental apparatus. Importantly, Y-Fi VUV can be used with a window between the source and the experimental chamber, guaranteeing that applications demanding ultrahigh vacuum (such as ARPES) will remain contamination-free.

In addition to ARPES, Y-Fi VUV will enable breakthrough research in photoelectron emission electron microscopy (PEEM), photoionization mass spectroscopy (PIMS) for combustion research, and other studies of next-generation materials and molecular systems.

The Y-Fi VUV 

  • Is discretely tunable
  • Provides high energy resolution
  • Enables femtosecond time-resolved experiments
  • Allows high spatial resolution 
  • Provides synchrotron-quality VUV in your lab


  • Angle-resolved photoemission spectroscopy (ARPES)
  • Time-resolved ARPES
  • Photoemission electron microscopy (PEEM)
  • Photo-ionization mass spectroscopy (PIMS)
  • Molecular time-of-flight (ToF) studies
  • Applications that require tunable VUV light
  • Applications that require femtosecond pulses of VUV light

Features that lead to significant benefits:

  • Tunable (computer-selected) photon energy between 6–10.8 eV enhances capabilities for laser ARPES experiments:
    • Achieve high momentum resolution using low energy photons (< 7 eV) and still cover higher momentum range using high photons (> 10 eV)
    • Obtain surface vs. bulk information
    • Reveal "hidden bands" by changing wavelength
    • Bandwidth is adjustable to optimize data collection
  • Tight focal spots provide greater sample flexibility, allowing the study of 
    • Extremely small samples
    • Spatially heterogeneous samples
    • Polycrystalline materials
  • A window provides complete isolation between the Y-Fi VUV and the experimental chamber, maintaining high vacuum
  • Femtosecond pulses enable time-resolved experiments
  • Y-Fi VUV measures only 2.5 feet x 5 feet, bringing the power of the synchrotron to your lab
Photon Energy Size Repetition Rate Power Stability
6.0, 7.2, 8.4, 9.6, 10.8 eV 2.5 x 5 feet
(0.75 to 1.5 meters)
1 Mhz <5% [RMS]
Photon Flux


Full bandwidth

(~40 meV)


Moderate bandwidth

(< 5 meV)

7.2 eV 1012 ph/s delivered

5x1010 ph/s delivered

10.8 eV 1010 ph/s delivered

5x108 ph/s delivered

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