The most accurate observations are made when we observe the light emitted when the vapour pressure is low . 当蒸气压很低时，可以对原子所发射的光谱作出最精确的观测。
Further work will be required to see if indeed two non-emitting triplet states exist in this region . 进一步的工作将是需要了解两种不发射的三重性态是否确实存在在这一范围。
This is found by observing the doppler shift in the frequency of the radio signals broadcast from the satellite . 这是通过观测卫星所发射的无线电信号频率中多普勒偏移来确定的。
Perplexed, they decided that the lines were not emitted by the commonplace oh molecule but an unknown substance . 他们很感迷惑地判定，这些谱线不是由寻常的OH分子而是由一种未知物质发射的。
This effect is particularly important for leds since the emitted spectral width is several hundred angstroms . 这种效应对于发光二极管来说是特别重要的，因为发光二极管所发射的光谱带宽可达几百埃。
In optics one usually deals with a source which emits light within a narrow, but nevertheless finite, frequency range . 在光学中，常常遇到的是这样的光源，它所发射的光频率范围虽窄，但仍有一定的宽度。
The results thus far obtained are rather divergent partly because different radiation are emitted at different heights . 迄今得出的结果颇为分歧，其原因，一部分是因为各种不同的辐射是在不同的高度上发射的。
Dover was engaged six times in september, the heaviest day being september 9, when over a hundred and fifty shells were fired . 多佛尔在9月间受到了六次轰击，最猛烈的一次是在9月9日，发射的炮弹超过一百五十发。
Astronomers have also detected older and smaller m stars, previously thought to be quite dim, that actually outshine the sun in their x-ray emission . 天文学家还探测到有一些较老较小的M型星，它们发射的X射线实际上比太阳更加光辉灿烂，而先前人们却认为它们是十分幽暗的。
Thunderstorms , though , could keep it on the ground 然而雷暴天气可能会影响发射的进程。
