displacement of spectral line 基本例句 谱线位移 This spectral shift permits laser light to selectively excite molecules containing one isotope while leaving the molecules containing the other isotope undisturbed.这种谱线位移使我们能够利用激光有选择地激发含有某一同位素的分子，而含有其他同位素的分子则完全不受扰动。