WHAT IT IS
The Nd:YAG 213 nm laser ablation system is a solid-state laser source widely used in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). It is based on a neodymium-doped yttrium aluminum garnet (Nd:YAG) crystal that emits at 1064 nm and is frequency-quadrupled to generate a deep ultraviolet wavelength of 213 nm. This wavelength is well absorbed by most solid samples, producing efficient material removal and aerosol generation. Nd:YAG 213 nm lasers offer a balance of robustness, affordability, and versatility, making them a standard choice in geochemistry, materials analysis, and applied sciences.
HOW IT WORKS
Laser Generation - The Nd:YAG crystal produces a fundamental infrared output at 1064 nm. Nonlinear optical crystals are used to successively multiply the frequency, producing the 213 nm UV output.
Beam Delivery - Mirrors and focusing optics guide the laser beam into the ablation chamber. Spot sizes can typically be adjusted from a few micrometers to >100 µm, depending on the resolution required.
Sample Interaction - Pulses at 213 nm are strongly absorbed by most minerals, metals, and synthetic solids. Energy deposition causes rapid vaporization, melting, and particle ejection from the surface.
Aerosol Transport - Helium or argon carrier gas flushes the ablated aerosol out of the chamber toward the ICP torch. The generated particles are atomized and ionized in the plasma.
Detection - Ions are separated and detected by the mass spectrometer, providing elemental and isotopic information at high sensitivity.
The 213 nm wavelength provides a compromise between deeper UV excimer lasers (193 nm) and longer-wavelength sources (266 or 1064 nm), offering good absorption efficiency with simpler, more robust solid-state technology.
ADVANTAGES
Broad Applicability: Efficient ablation across a wide range of geological, biological, and synthetic materials.
Compact and Robust: Solid-state design requires less maintenance than gas-based excimer lasers.
Cost-Effective: More affordable than 193 nm excimer or femtosecond laser systems.
Resolution Flexibility: Adjustable spot size and repetition rate support both micro-analysis and bulk profiling.
Stable Operation: Produces consistent energy per pulse with good long-term reliability.
Routine Standard: Well established in LA-ICP-MS laboratories, with extensive application data and validated methods.
CHALLENGES AND LIMITATIONS
Elemental Fractionation: Nanosecond pulses at 213 nm still produce some melting and fractionation, reducing stoichiometric transfer compared with femtosecond lasers.
Matrix Effects: Ablation efficiency varies between different materials, which can complicate quantification.
Resolution Limit: Cannot achieve the sub-micron resolution possible with femtosecond sources.
Performance vs Excimer: Excimer lasers at 193 nm offer higher absorption efficiency and reduced fractionation, though with higher cost and complexity.
Maintenance Needs: While simpler than excimer systems, optics alignment and crystal care are still required.