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P/B比
peak-to-background ratio
[目次：分光分析]
1）EELS でのスペクトルのピークとバックグラウンドの比。ELNESの場合、高いバックグラウンドの上に信号乗るのでP/B比は悪い。入射電子線の加速電圧が高くなると、多重散乱の減少と有効取り込み角の増大のためにP/B比は増大する。2）EDSでの特性X線の強度とバックグラウンドの比。TEMの場合のP/B比は非常に良い。加速電圧が高くなると制動放射を起こす確率が減り、バックグラウンドが減るためにP/B比は増大する。
The "peak-to-background ratio" is defined as the ratio of the peak intensity to the background intensity in a spectrum. (1) In an ELNES spectrum of EELS, the ratio is low because of its high-background signal. As the accelerating voltage of the incident electron beam is increased, the peak-to-background ratio is improved, because multiple scattering is decreased and the effective acceptance angle is increased. (2) In an EDS spectrum measured in a TEM, the ratio of the characteristic X-ray peak intensity to the background intensity is very high. When the accelerating voltage is increased, the ratio is further improved because the probability of bremsstrahlung (background) is decreased.