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XPSPEAK

 

Shirley + Linear Background

1. The Shirley + Linear background has been added for sloping backgrounds

· The "Shirley + Linear" background is the Shirley background plus a straight line with starting point at the low BE end-point and with a slope value

· If the slope value is zero, the original Shirley calculation is used

· If the slope value is positive, the straight line has higher values at the high BE side, which can be used for spectra with higher background intensities at the high BE side

· Similarly, a negative slope value can be used for a spectrum with lower background intensities at the high BE side

2. The Optimization button may be used when the Shirley background is higher at some point than the signal intensities

· The program will increase the slope value until the Shirley background is below the signal intensities

· Please see the example below - Cu2p_bg.xps - which shows background subtraction using the Shirley method (This spectrum was sent to Dr Kwok by Dr. Roland Schlesinger).

· A shows the problematic background when the Shirley background is higher than the signal intensities. In the Shirley calculation routine, some negative values were generated and resulted in a non-monotonic increase background

· B shows a "Shirley + Linear" background. The slope value was input by trial-and-error until the background was lower than the signal intensities

· C was obtained using the optimisation routine

A slope = 0

B slope = 11

C slope = 15.17

Note: The background subtraction calculation cannot completely remove the background signals. For quantitative studies, the best procedure is "consistency". See Future Versions, (Page 2).

Tougaard

For a Tougaard background, the program can optimise the B1 parameter by minimising the "square of the difference" of the intensities of ten data points in the high binding energy side of the range with the intensities of the calculated background.

Adding/Adjusting the Background

Note: The Background MUST be correct before Peaks can be added. As with all backgrounds, the range needs to include as much of your peak as possible and as little of anything else as possible.

1. Make sure the file of interest is open and the appropriate region is active

2. Click on Background in the upper window

· The Region 0 box comes up, which contains the information about the background

3. Adjust the following as necessary. See Note.

· High BE (This value needs to be within the range of your data)

· Low BE (This value needs to be within the range of your data)

NOTE: High and Low BE are not automatically within the range of your data. CHECK CAREFULLY THAT BOTH ENDS OF THE BACKGROUND ARE INSIDE THE EDGE OF YOUR DATA. Nothing will happen otherwise.

· No. of Ave. Pts at end-points. See Averaging, (Page 7)

· Background Type

· Note for Shirley + Linear:

To perform the Shirley + Linear Optimisation routine:

a) Have the file of interest open

b) From the upper window, click on Background

c) In the resulting box, change or optimise the Shirley + Linear Slope as desired

· Using Optimize in the Shirley + Linear window can cause problems. Adjust manually if necessary

3. Click on Accept when satisfied

Adding/Adjusting Peaks

Note: The Background MUST be correct before peaks can be added. Nothing will happen otherwise. See previous section.

· To add a peak, from the Region Window, click on Add Peak

· The peak window appears

· This may be adjusted as below using the Peak Window which will have opened automatically

In the XPS Peak Processing (lower) window, there will be a list of Regions, which are all the open files, and beside each of these will be numbers representing the synthetic peaks included in that region.

Synthetic Peaks

Regions (files)

1. Click on a region number to activate that region

· The active region will be displayed in the upper window

2. Click on a peak number to start adjusting the parameters for that peak.

· The Processing window for that peak will open

3. Click off Fix to adjust the following using the maximum/minimum arrow keys provided:

· Peak Type. (i.e. orbital – s, p, d, f)

· S.O.S (Δ eV between the two halves of the peak)

· Position

· FWHM

· Area

· %Lorenzian-Gaussian

· See the notes for explanations of how Asymmetry works.

4. Click on Accept when satisfied

Peak Types: p, d and f.

1. Each of these peaks combines the two splitting peaks

2. The FWHM is the same for both the splitting peaks, e.g. a p-type peak with FWHM=0.7eV is the combination of a p_3/2 with FWHM at 0.7eV and a p_1/2 with FWHM at 0.7eV, and with an area ratio of 2 to 1

3. If the theoretical area ratio is not true for the split peaks, the old way of setting two s-type peaks and adding the constraints should be used.

· The S.O.S. stands for spin orbital splitting.

Note: The FWHM of the p, d or f peaks are the FWHM of the p_3/2, d_5/2 or f_7/2, respectively. The FWHM of the combined peaks (e.g. combination of p_3/2 and p_1/2) is shown in the actual FWHM in the Peak Parameter Window.

TTHE NEW YORK TIMES:Western Experts Monitor China’s Nuclear Sites for Signs of Earthquake Damage

"China’s main complex for making nuclear warhead fuel, codenamed Plant 821, is beside a river in a hilly, forested part of the earthquake zone. It is some 15 miles northwest of Guangyuan in Sichuan Province. The vast site holds China’s largest production reactor and factories that mine its spent fuel for plutonium — the main ingredient for modern nuclear arms.

"It is unclear if the plutonium-production reactor at Plant 821 has operated recently. Mr. Kristensen of the Federation of American Scientists said China was expanding its nuclear forces to 240 warheads in its overall stockpile from around 200.

"A senior federal official, who spoke on the condition of anonymity because of the delicacy of the issue, said the United States was using spy satellites and other means to try to monitor the sprawling nuclear plants. “There appear to be no immediate concerns,” the official said."

Why the Americans are always telling us Chinese People what has happened in China?  And our government will never publish it until the whole word have know it but we Chinese People.