Signal Amplification via Nonlinear Femtosecond Laser Filamentation for Trace Metal Ion Detection Using Metal–Organic Framework–Polymer Adsorbents

Signal amplification strategies are essential for enhancing the sensitivity and accuracy of analytical methods. This study introduces an innovative approach that utilizes the nonlinear process of femtosecond laser filamentation as a signal amplifier in combination with metal-organic framework (MOF)-polymer adsorbents. In this method, metal ions adsorbed in the MOF-polymer composite alter the intensity and temporal characteristics of an 800 nm femtosecond laser pulse. These changes significantly impact the spectra produced after filamentation, thus serving as an effective signal amplifier. Using MOF single crystals as metal ion enrichment platforms, we enhance spectral signals and achieve detection limits as low as 0.1 ppb for trace metal ions. The integration of the MOF adsorbent with the extensive spectral modifications induced by femtosecond laser filamentation represents a significant advancement in signal amplification techniques for analytical chemistry and environmental monitoring.