박성만 (강원대학교 )

권찬호 (강원대학교)

박성만 (강원대학교 )

권찬호 (강원대학교)

Accurate gas-phase spectroscopic analysis of thermally sensitive, non-volatile organic and biomolecules is essential for probing their intrinsic structural and electronic properties. Conventional mass spectrometric methods, which rely on thermal vaporization, often induce fragmentation or structural alteration, limiting analytical accuracy. Laser desorption/ionization (LDI) techniques such as MALDI, SALDI, and the more advanced MALDI-2 have been developed to mitigate thermal degradation. However, these methods typically couple desorption and ionization within a single-laser or collinear laser scheme, which restricts wavelength flexibility and reduces control over energy deposition, thereby affecting reproducibility and selectivity.

Here, we present a decoupled two-stage laser desorption–photoionization system that enables soft, interference-free ionization of intact molecules. The desorption laser operated in the UV–IR range, while photoionization was carried out using a high-intensity vacuum ultraviolet (VUV) laser. Desorption was conducted using a variety of substrates—graphite powder, silver foil, stainless steel, and adhesive tape—selected for their differing thermal and optical properties. A molecular beam pickup strategy was implemented to reduce background signals and thermal decomposition, with precise control over the delay between the two laser pulses. Desorption yields and ionization efficiencies were quantitatively compared across conditions.

Compared to MALDI-2, this decoupled approach offers greater flexibility in substrate selection in place of conventional matrix use, enhanced wavelength tunability, and improved temporal control over the desorption and ionization processes. This methodology enables accurate determination of ionization energies for thermally labile, non-volatile molecules and establishes a robust platform for high-resolution gas-phase spectroscopic and mass spectrometric analysis.