Re: [問題] 請問大家一個關於FT儀器的問題
※ 引述《innevertears (士乎)》之銘言：
: 如題
: 今天寫考古題的時候，有碰到一題
: 為何有FT-IR但卻沒有FT-UV/Vis
: 參考書上面的答案是寫
: 「因為IR的光源弱，屬於熱偵測器，可用FT的技巧改善S/N ratio
: 而UV的光源強，偵測器屬於photo type，所以用FT的改善效果不大」
: 後來我自己又去翻了skoog的IR和UV的章節
: 也沒有找到相關敘述
: 覺得答案好像少了一些關鍵點
: 沒有解釋為何光源強和光源弱改善效果上的差別
: 不知道有沒有其他更好的答案，或是這已經是答案了呢?
: 先謝謝大家!
我有相同的問題，但是找到答案之後卻看不懂，是否有高人可以指點一下？
每個英文大致看得懂，但合在一起卻莫宰羊啊…Q_Q、、
還有，為何光源會閃爍呢？
“Fourier transform instruments are much less common for the
ultraviolet, visible and near-infrared region, however, because
signal-to-noise limitations for spectral measurements with these
types of radiation seldom lies in detector noise but instead in
shot noise and flicker noise associated with the source. In
contrast to detector noise, the magnitudes of both shot
and flicker noise increase as the power of the signal increases.
Furthermore, the total noise for all of the resolution elements in
a Fourier transform measurement tends to be averaged and spread
out uniformly over the entire transformed spectrum. Thus, the
signal-to-noise ration for strong peaks in the presence of weak
peaks is improved by averaging but degraded for the weaker peaks.
For flicker noise, such as is encountered in the background radiation
from many spectral sources, degradation of S/N for all
peaks is observed. This effect is sometimes termed the multiplex
disadvantage and is largely responsible for the fact the Fourier
transform has not been widely applied for ultraviolet/visible
spectroscopy.”1
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