x****s
发帖数: 591 | 1 我们用的是Perkin Elmer Spectrum One FTIR， ATR是 ZnSe
扫background的时候，会给出两个Y轴单位的选择ArbY和EGY, 想请教一下，这俩分别是
什么，区别在哪呢? |
y****i
发帖数: 1504 | |
x****s
发帖数: 591 | 3 先谢谢yaofei呀
那如果光谱y轴需要用吸收率（A），扫background的时候，Y轴单位是不是应该选择
ArbY？
因为还是不明白ArbY和EGY分别什么时候用。。
谢谢啦 |
d********y
发帖数: 176 | 4 the unit of energy is arbitrary anyway and so it really doesn't matter what
you choose.
i never worry about the unit for the background scan on PE One. similarly i
never worry about the unit for the actual spectrum because you can always
convert them later. |
x****s
发帖数: 591 | |
x****s
发帖数: 591 | 6 想再请教一个问题呀～
图片里面X轴，波长是4000－650，Y轴，吸收率-0.0487到0.0268 样品是表面为金的Si
wafer， 128scans
我发现有时候得到的图会倾斜得很厉害，主要是什么原因呢 如何避免倾斜？
因为有时候会比这个图倾斜得更厉害。。
请大家轻拍呀～ 谢谢 |
d********y
发帖数: 176 | 7 what are you trying to measure? Au on Si isn't a good sample for the ATR
mode. you should consider reflection absorption on highly reflective
surfaces and if your sample is only a few monolayers/submonolayer.
to answer your question - there are several reasons behind the tilted bkgd.
one is due to the reflective nature of Au, one is that it isn't really that
tilted if you look at the y-scale. you won't even notice it if your sample
has an absorbance around 0.5. another reason is simply system drift. |
b******k
发帖数: 37 | 8 请问如果是FTIR reflectance measurements, 纵坐标是reflectance 还是 absorption？
.
that
【在 d********y 的大作中提到】
: what are you trying to measure? Au on Si isn't a good sample for the ATR
: mode. you should consider reflection absorption on highly reflective
: surfaces and if your sample is only a few monolayers/submonolayer.
: to answer your question - there are several reasons behind the tilted bkgd.
: one is due to the reflective nature of Au, one is that it isn't really that
: tilted if you look at the y-scale. you won't even notice it if your sample
: has an absorbance around 0.5. another reason is simply system drift.
|
x****s
发帖数: 591 | 9 想问问我6楼那个图呀。。 我是用空气做background， 仪器内部没有干燥剂也没惰性
气体。。
图中最右边650－670那一段大波动是不是水气和二氧化碳呢？ |
d********y
发帖数: 176 | 10 gas phase water O-H stretch is between 4000-3000 and its bending ~1640
CO2 is between 2400-2280.
the big fluctuation (again it isn't really big if you have an absorption
band >0.2) is due to the bad S/N ratio, which is in turn due to the low IR
power reaching the detector. if you look at the bkgd scan, you'll find
that there is very little energy between 650-670. this is due to ZnSe cut
off.
【在 x****s 的大作中提到】
: 想问问我6楼那个图呀。。 我是用空气做background， 仪器内部没有干燥剂也没惰性
: 气体。。
: 图中最右边650－670那一段大波动是不是水气和二氧化碳呢？
|
|
|
d********y
发帖数: 176 | 11 they are related just like transmission and absorption are related. for
details, google infrared reflection absorption spectroscopy【 在 bigshark
(鲨鱼) 的大作中提到: 】
absorption？ |
d********y
发帖数: 176 | 12 i forgot to mention that gas phase IR spectra usually have P/R branches
with many sharp bands. the feature you mentioned didn't have that.
IR
cut
【在 d********y 的大作中提到】
: gas phase water O-H stretch is between 4000-3000 and its bending ~1640
: CO2 is between 2400-2280.
: the big fluctuation (again it isn't really big if you have an absorption
: band >0.2) is due to the bad S/N ratio, which is in turn due to the low IR
: power reaching the detector. if you look at the bkgd scan, you'll find
: that there is very little energy between 650-670. this is due to ZnSe cut
: off.
|
x****s
发帖数: 591 | 13 thx davidcrazy~
这样的话，ZnSe cutoff 有什么办法最大限度减低么
谢啦 |
d********y
发帖数: 176 | 14 no way with ZnSe. you can try other ATR elements like diamond and may get
down to 550
but like i said above, you may not want to use ATR anyway for your sample
system.
【在 x****s 的大作中提到】
: thx davidcrazy~
: 这样的话，ZnSe cutoff 有什么办法最大限度减低么
: 谢啦
|
x****s
发帖数: 591 | 15 THX davidcrazy
其实也有考虑过，Grazing angle infrared，不知道可行不？
如果只能做FTIR-ATR的话，是不是该把图截到700 好了？
【在 d********y 的大作中提到】
: no way with ZnSe. you can try other ATR elements like diamond and may get
: down to 550
: but like i said above, you may not want to use ATR anyway for your sample
: system.
|
x****a
发帖数: 1041 | 16 扫背景的时候把压力也load上去。否则扫样品和背景时，晶体上的压力不同，光路会有
微小差别，基线就会斜。
Si
【在 x****s 的大作中提到】
: 想再请教一个问题呀～
: 图片里面X轴，波长是4000－650，Y轴，吸收率-0.0487到0.0268 样品是表面为金的Si
: wafer， 128scans
: 我发现有时候得到的图会倾斜得很厉害，主要是什么原因呢 如何避免倾斜？
: 因为有时候会比这个图倾斜得更厉害。。
: 请大家轻拍呀～ 谢谢
|
