Fluorometric Beam Profiling of UV MALDI Lasers

  • Rory T. Steven
  • Andrew D. Palmer
  • Josephine Bunch
Research Article


The photon distribution (beam profile) of the laser as projected onto the sample is an important variable in matrix assisted laser desorption ionization mass spectrometry (MALDI-MS). Measurement of the beam profile is, therefore, an important factor within MALDI-MS. In this study a simple, low-cost fluorometric laser beam profiling technique is presented and applied in conjunction with MALDI-MS experiments. A comparison of the beam profile information afforded by a commercial system and the fluorometric method is carried out to determine the variation of beam profile for an Nd:YVO4 laser operated between 1 and 25 kHz. The beam profile information can be used, in conjunction with corresponding ion yields, to inform MALDI-MS experiments. The fluorometric beam profiling technique is used to obtain information about the beam dimensions as incident upon the MALDI-MS sample plate in-source. These values are compared with equivalent information obtained from ablation of thin film α-cyano-4-hydroxycinnamic acid (CHCA). In this study, area estimation by ablation provided a value 1.6 times smaller than that obtained by the fluorometric method, demonstrating the need for caution when measuring beam profile and, therefore, fluence, in MALDI-MS.

Key words

Laser beam profiling MALDI-MS UV laser MALDI ionization Fluorescence Laser spot size 

Supplementary material

13361_2013_650_MOESM1_ESM.pdf (406 kb)
ESM 1 (PDF 406 kb)


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Copyright information

© American Society for Mass Spectrometry 2013

Authors and Affiliations

  • Rory T. Steven
    • 1
    • 2
  • Andrew D. Palmer
    • 1
    • 2
    • 3
  • Josephine Bunch
    • 1
    • 2
  1. 1.PSIBS Doctoral Training CentreUniversity of BirminghamBirminghamUK
  2. 2.School of ChemistryUniversity of BirminghamBirminghamUK
  3. 3.School of Computer ScienceUniversity of BirminghamBirminghamUK

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