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】![](/moin_static193/solenoid/img/up.png) : 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.
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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】![](/moin_static193/solenoid/img/up.png) : 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?
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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】![](/moin_static193/solenoid/img/up.png) : 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.
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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】![](/moin_static193/solenoid/img/up.png) : thx davidcrazy~ : 这样的话,ZnSe cutoff 有什么办法最大限度减低么 : 谢啦
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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】![](/moin_static193/solenoid/img/up.png) : 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.
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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】![](/moin_static193/solenoid/img/up.png) : 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
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