Acquisition of a femtosecond laser ablation system

这项提案寻求60,000美元的资金，用于部分购买飞秒激光消融系统(FSLA)，作为威斯康星大学麦迪逊分校放射成因同位素实验室现有多收集器电感耦合等离子体质谱仪的样品引入系统。该大学将出资35.5万美元，美国国家航空航天局将出资6万美元。通过波长更短、脉宽更快的激光消融系统，同位素测量可能会得到改进。波长在深紫外光和飞秒脉冲宽度的系统正开始在地球科学界部署。最近的研究表明，当使用FSLA烧蚀时，含有锶、铅和氢等元素的放射性同位素比率从源物质中得到更好的保存。最初实验的主要目标是测量微生物还原Fe3+产生的单个碳酸盐中的铁同位素。FSLA系统将是必要的，以梳理出铁的分馏因素，而这在整体分析中是不可能的。对块状碳酸盐的测量尤其具有挑战性，因为铁同位素在溶解过程中往往会发生分馏。当进行连续的酸消化时，这种影响是明显的。FSLA系统应该允许对单个碳酸盐进行分析，以减轻这种偏差。PI提供了相当多的证据支持FSLA系统，而不是微探针或SIMS分析。建议同时使用SIMS和FSLA进行组合分析。FSLA系统将为UW-M提供广泛的分析可能性。学生和博士后将能够使用该系统。虽然铁同位素将是最初的焦点，但沉积和火成岩地球化学将受益于较短的脉冲激光消融。锆石U-Pb和Hf分析将成为可能。与密歇根大学稀有气体实验室的合作努力也将显而易见。*

0901938JohnsonThis proposal seeks funding of $60K for partial purchase of a femtosecond laser ablation system (fsLA) to be used as an sample introduction system on an existing multi-collector ICP-MS system within the Radiogenic Isotope Laboratory at UW-Madison. The University will contribute $355K and NASA will contribute $60K toward the purchase. Isotope measurements may be improved by shorter wavelength, faster pulse-width laser ablation systems. Systems with wavelengths in the deep UV and femtosecond pulse widths are beginning to be fielded in the geoscience community. Recent studies show radiogenic isotopes ratios with elements like Sr, Pb and Hf are better preserved from source material when ablated using fsLA. The prime goal for initial experiments is measuring Fe isotopes in individual carbonates produced by microbial Fe3+ reduction. The fsLA system will be necessary to tease out Fe fractionation factors which would not possible with bulk analyses. Measurements with bulk carbonates is particularly challenging because Fe isotopes tend to fractionate during dissolution. The effect is noticeable when sequential acid digestions are performed. The fsLA system should allow individual carbonates to be analyzed mitigating this bias. The PIs present considerable evidence to support the fsLA system over microprobe or SIMS analyses. Combination analysis with both SIMS and fsLA is suggested. The fsLA system will offer a wide range of analytical possibilities to UW-M. Students and post-docs will be able to utilize the system. While Fe isotopes will be initial focus, sedimentary and igneous geochemistry will benefit from shorter pulse laser ablation. Zircon U-Pb and Hf analyses will be possible. Collaborative efforts with the Rare Gas Laboratory at UW-M will also be evident.***