摆度
第1楼2015/04/22
Answer 1 & 2: You need to understand some fundamental such as what XPS can tell you, what is purpose of what we called as "survey" & "narrow scan" (全谱 & 窄谱). And also, you need to understand in XPS instrument there are parameter settings such as "Pass Energy" (通过能), Energy Step and Dwell time.
(1)XPS = Its a surface analysis technique which tell you the ELEMENTAL & CHEMICAL information of the top surface (~5nm or say less than 10nm) on your sample. It can also do semi-quantification.
(2)Survey = when doing a survey, usually the purpose is really to know what presence on the sample (ELEMENTAL information). At this step, you do not care about chemical info and quantification. The concept of a survey should be done quickly and typically just about 5-20 minutes.
(3)Narrow scan = purpose of narrow scan is to in-detailed study the interested selected elements. In your case, you showed Co+Mn+Si. When looking at the narrow scan, you can judge details like Chemical information (by peak position & peak shape), and then also do quantification (integral area of the peak).
(4) Pass Energy (PE), step size & Dwell
e.g. For a survey, usually using higher PE (depending on instrument), bigger step size (e.g. 1eV/step), and shorter dwell time.
High PE = high intensity but poor energy resolution (meaning fat peak) >>> then Low PE is opposite (good energy resolution meaning thin peak)
Step size = # of data points
Dwell time = the time for the instrument to look at each energy step size.
e.g. Your survey showed the spectrum from 1350eV to 0eV. Say if it is 1eV step size and dwell time 50ms. Then total analysis time will be:
total step = 1350/1 + 1 = 1351
Time for 1 scan = 1351 x 50ms = 67.55s
e.g. Narrow scan example = take your Mn2p as example.
Spectrum range 661 to 633eV. I think it looks like 0.1eV step size. If dwell time is 50ms.
Then just Mn2p element time will be:
total step = (661-633)/0.1 + 1 = 281
Time for 1 scan = 281 x 50ms = 14.05s
So at this point, I think you can understand answer to question 1 is after zooming in the same range in survey (e.g. Mn) and compare to the narrow scan, then they will NOT be the same. You will expect the survey will be higher count BUT peak is FAT, then narrow scan although count is low but PEAK itself would be thinner and support should be "smoother".
And then answer to question 2 is because survey is using high PE and narrow scan is using low PE (Pass Energy).
Answer 3: Your survey spectrum is ok (meeting purpose of identifying the presence elements). But narrow scan the signal-to-noise is bad. If longer time can be spent for the narrow scan I think data can be better.
Answer 4: Again, it is the signal-to-noise not good enough. You feel the peaks are FAT and I think for Mn maybe more than 1 chemical state is presence here.
Answer 5: Quantification is calculated by integral area of the peaks and also sensitivity factors (provided by instrument maker).
Answer 6: Theoretically it will not affect for the coated Pd. What I can say is thinner the better. Because as mentioned in the beginning XPS is a surface analysis technique and detection sampling depth is 5-10nm only. If its too thicker, sure then it will start to affect your data.