Harilal S S, Miloshevsky G V, Sizyuk T, Hassanein A
Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
Phys Plasmas. 2013 Jan;20(1):13105. doi: 10.1063/1.4775725. Epub 2013 Jan 11.
Laser-produced nitrogen plasmas emitting radiation at 2.48 nm (Ly-α) and 2.88 nm (He-α) are considered potential efficient sources for water-window (WW) microscopy. The atomic and optical properties of nitrogen plasma and influence of the laser wavelength on the line emission in the WW range are investigated. It is found that the optimal temperatures for maximum emission from Ly-α and He-α spectral lines are 40-60 eV and 80-100 eV, respectively. The WW line emission and the conversion efficiency (CE) are estimated for three distinct Nd:YAG laser wavelengths (1064 nm, 532 nm, and 266 nm). The calculated CEs are compared with experimentally observed CE values. It is found that 1064 nm wavelength provides the highest CE from laser to Ly-α and He-α radiation.
发射2.48纳米（Ly-α）和2.88纳米（He-α）辐射的激光产生的氮等离子体被认为是水窗（WW）显微镜潜在的高效光源。研究了氮等离子体的原子和光学性质以及激光波长对水窗范围内线发射的影响。发现Ly-α和He-α光谱线最大发射的最佳温度分别为40 - 60电子伏特和80 - 100电子伏特。针对三种不同的Nd:YAG激光波长（1064纳米、532纳米和266纳米）估算了水窗线发射和转换效率（CE）。将计算得到的转换效率与实验观测的转换效率值进行了比较。发现1064纳米波长从激光到Ly-α和He-α辐射提供了最高的转换效率。
