为研究气压对激光诱导击穿光谱检测性能的影响，实验研究了0.01～100.00 kPa大气压强下钢铁样品中Fe I 438.35 nm和Fe I 404.58 nm谱线的强度、寿命、信噪比及相对标准偏差随采集时间的演化。结果表明，大气压强从100.00 kPa逐渐下降至0.01 kPa时，大气与等离子体的相互作用减小，导致等离子体光谱强度逐渐减小至原来的1/20，谱线寿命从常规的几十微秒逐渐缩短至只有2.5 μs；谱线的信噪比随气压降低逐渐减小，相对标准偏差在气压降低至0.1 kPa以下时迅速增大。这说明气压降低会导致光谱质量变差，为保证分析灵敏度，低气压下应选择较短的采集时延；当气压低于0.10 kPa时，分析谱线的相对标准偏差迅速大于10%。

To investigate the effects of atmospheric pressure on the performance of laser-induced breakdown spectroscopy, thetemporal evolution of the intensities, lifetimes, signal-to-noise ratiosand relative standard deviation of Fe I 438.35 nm and Fe I 404.58 nm spectral lines were experimentally analyzed. The results show that, when the pressures are decreased from 100.00 kPa to 0.01 kPa, the intensities are reduced to 1/20 of the original values; the lifetimes reduce gradually from tens of microseconds to only 2.5 μs, while the signal-to-noise ratios gradually reduce and relative standard deviations increases.This indicates that a reduction in pressure can cause deterioration of the spectrum quality, to ensure the analysis sensitivity a shorter acquisition time delay should be selected for a low pressure; when the pressure is lower than 0.10 kPa, the relative standard deviations of the lines begin to exceed 10% quickly.