Read Chapter 1: Collecting Data text version

XRD User Manual

(Revised and Updated 11/21/08)

for the Rigaku Geigerflex D/Max IIA X-ray Diffractometer & MDI DataScan4 Software

Materials Analysis Training & Education Center Department of Materials Science and Engineering North Carolina State University Raleigh, NC

TABLE OF CONTENTS

Page Chapter 1: Collecting Data Section 1: Powering on the XRD Instrument ............................................................1 Section 2: Sample Mounting and Selecting the Appropriate Slits..............................2 Section 3: Setting up a /2 XRD Scan .....................................................................4 Section 4: Recording and Saving XRD Scans ............................................................8 Section 5: Shutting Down the Instrument...................................................................9 Chapter 2: XRD Data Section 1: Accessing the JCPDS cards .....................................................................11 Section 2: Ghost peaks..............................................................................................12 Chapter 3: Appendix Section 1: Instrument Specifications ........................................................................13 Section 2: Theta/2-Theta Alignment using TALK ...................................................13 Chapter 4: Troubleshooting Section 1: Instrument Problems ................................................................................16

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Chapter 1: Collecting Data

Only trained authorized users may use the XRD instrumentation!!!

1.1 Powering On The Rigaku XRD Instrument

Chilled Water If the Haskris heat exchanger (chilled water) is not on, then flip the switch on. (You should hear the heat exchanger pump turn on). If not already open, then slowly turn on both lever operated quarter-turn ball valves to the open position with the lever handles aligned with the valve body hoses (vertical position). These valves are located at the ceiling and connected directly to the Rigaku cooling lines. Check the water flow meter to ensure there is sufficient water flow with the marker about 1/3 distance from the bottom of the sight tube. Check the Hour Meter and Fill in the Log Book The hour meter is located on the x-ray generator cabinet inside the right-hand door at the lower right-hand corner. Record the displayed reading in the log book along with your name, principle investigator's name, account number, and the material analyzed. Also be sure that the doors on the machine are closed and that the shutters are closed.Check to make sure that the Rigaku Control Console, Databox and PMT high voltage supply are also on. Press the Red "ON" Switch The fluorescent light should come on. If buzzing alarm comes on and stays on for longer than 5 seconds, then turn off the instrument and contact the TA in charge. The white xray ready light should come on. If this is not the case check to be sure that the current and voltage switches are at their lowest positions and that the sliding shield doors are fully closed. Press the "X-RAY ON" Switch Down The red light over the switch should come on and the red light over the goniometer should light up.

Slowly Turn Up the Voltage and Current Levels First slowly turn up the voltage to 27.5 kV and then slowly the current to 20 mA. If you are the first one to use the instrument that day take about 3 to 4 minutes to do this; otherwise 1 to 2 minutes is sufficient between successive scans. Do Not Exceed These Current And Voltage Levels. Before Opening the Sliding Door Each Time Turn down the voltage and current and shut off the x-ray generator. To restart a scan check the conditions for the X-ray lamp lighted are in place and then restart X-ray on followed by bringing the voltage and current back up to 27.5 kV and 20 mA respectively. Before Beginning a Scan Open shutter #2 after closing the doors and before starting a scan.

1.2 Sample Mounting and Selecting the Appropriate Slits

Sample holder If you designed your own holder that is most appropriate for your particular sample, then the thickness of the holder shall not exceed 0.065 inches at the end used to insert into the retaining clips. One should always run a scan of one's own empty holder with different slit sizes to be sure that no peaks from the holder are detected, and also to provide background estimation. The specimen holder typically uses a glass plate attached to the back over a hole in an A1uminum or Plexiglas plate. To mount the sample on this specimen holder, put a small ball of mounting material, such as soft clay in the center of the glass plane on the side where the glass plate creates a recess. If you use clay be sure that your sample completely covers it since clay often has crystalline matter associated with it. The: surface sample should then be placed on the mounting material such that the surface of the specimen that you wish to analyze is in the same plane as the top surface of the metal part of the holder. This is usually done by pressing the sample into the mounting material with a glass slide. Damage to the surface of the sample can be minimized by slipping a piece of weighing paper or wax paper between the sample and the glass. Since the beam is a vertical line, it is best to mount the sample with its longer axis in the same direction ns the long axis of the sample holder to insure the highest possible signal. Remember that sample orientation is very important; as it will affect the XRD peak positions so be sure to be very careful. When you place the sample in the machine the front of the sample should be facing you when the machine is at 10 degrees

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and the clips should be on the backside. Be careful to center the sample on the mounting block and do not bend or force the spring clips back that hold the specimen tightly up against the block. If the sample and or its holder are loose and free to move, then the scan will produce unreliable data. Thus do not continue, but contact the XRD TA. Standard Slits See Figure 1 for a schematic of the slit arrangement. The slits with the blue edge are known as the standard slits, as they are the combination of slits most often used. We ask that you leave these slits in the machine when you are finished using it. The blue top edge and blue side edge should face you when the machine is at 10 degrees. These slits are: 1st slit (DS): 1° 2nd slit (SS): 1° 3rd slit (RS): 0.60 mm 4th slit (RSM): 0.80 mm

Figure 1. Schematic 2-dimensional view of the slit arrangement.

1st slit: Diffraction Slit (DS) This slit defines the irradiated sample area, which is dependent on the 2 Theta angle. A narrower slit will tend to give slightly lower noise (and slightly better resolution), however, if your sample area is larger than the area irradiated you will benefit in signal intensity by going to a larger slit. Typically for narrow samples (<7 mm) 1° is OK; for wider samples (between 7 and 20 mm) use 2° or 4° slit. 3

2nd slit: Scattering Slit (SS) Identical in purpose to the DS slit, therefore, DS and SS should match. However, note that the actual physical slits are neither identical nor interchangeable. 3rd slit: Receiving Slit (RS) In most cases this should be left at 0.6 mm. A smaller slit will cut down on your signal excessively. Perhaps the only reason to use a smaller slit is for rocking curve measurements or goniometer alignment. A larger slit will decrease your signal/noise ratio and broaden your peaks. 4th slit: Receiving Slit Monochromator (RSM) This should be left at 0.80 mm. Narrower slits cut down on your signal excessively but still not allow you to resolve the K1 from the K2. A slit of 0.05 mm would be needed to do this, but at a cost of >16X in intensity. Wider slits produce only a very slight improvement of signal (5%) but will allow impurity peaks, such as, Cr, W into the detector.

1.3 Setting Up a /2 XRD Scan

(For setting up /2 alignment using TALK (DOS command) software see Appendix) (TALK will not record scan data.)

1.3.1 Performing a Coarse /2 Goniometer Alignment

It is not necessary to turn on the X-Ray Generator for the alignment procedure in this Section. 1. From the PC desktop, mouse click on the DataScan4 icon. (This step checks the MDI Databox and if pre loads the goniometer drive motor parameter, if needed. 2. If OK, then there should be text information displaying: "XRD controller MDI Databox ready" and "MDI DataScan4 ­ MDI Databox Ready" at the bottom of the window. 3. From the DataScan4 menu bar, choose Control and MDI Databox and the Drive tab. Note the positions shown in the middle of the window for 2 (Detector) and (Theta). Normally these will be 10.0º and 5.0º, respectively. Look at the goniometer and make sure that the positions displayed agree with the goniometer alignment marks. The inner ring is the position with marks for 5º, and the outer ring reads the 2 position with a mark for 10º. If the marks appear closely align, then proceed to the Fine /2 Alignment steps in Section 1.3.2:

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4. If the marks are noticeably misaligned, then roughly align the goniometer using the Drive control options in MDI Databox window per the following procedures. 1.3.1.1 Coarse alignment of the Sample Theta goniometer 1. Enter the estimated misalignment in degrees in the Drive to: box by adding/ subtracting the estimated deviation to/from 5.0º. If unsure, then start with small angle values 2. Choose and select Axis:Theta Axis. This step is uncoupling the theta and 2 goniometer drives and selecting only the theta axis on which is rotates the sample. 3. Click on Go to bring the marks on the theta goniometer into alignment with each other. If the theta goniometer moves in the wrong direction with the marks moving farther apart rather than closer, then add (subtract) instead of subtract (add) from 5.0º. 1.3.1.2 Coarse alignment of the Detector 2-Theta goniometer 1. Enter the estimated misalignment in degrees in the Drive to: box by adding/ subtracting the estimated deviation to/from 10.0º. 2. Choose and select Axis:Detector axis. This step is uncoupling the and 2 goniometer drives and selecting only the 2 axis on which is mounted the detector. 3. Click on Go in order to bring the alignment marks on the 2 goniometer into alignment with each other. If the 2 goniometer moves in the wrong direction, then add (subtract) instead of subtract (add) from 10.0º.

IMPORTANT: Upon completion of the Coarse Alignments in section 1.3.1.1 or 1.3.1.2 then it is most imperative that both goniometer axis' are coupled using the following procedure in 1.3.1.3.

1.3.1.3 Recouple the and 2 goniometer drives 1. Open the CONTROL option on the menu bar and select MDI Databox from the drop down menu. 2. Choose and select for Axis: Both axis 3. Enter 10.0º for Detector (2) and 5.0º for Theta

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1.3.2 Performing a Fine Theta//2-Theta Goniometer Alignment

It is necessary to turn on the X-Ray Generator for this alignment procedure. 1.3.2.1 Check the Theta/2-Theta Alignment 1. Per section 1.2 insert the Si(004) sample provided or (optionally) use a well known peak from your own sample. 2. From the Datascan4 menu bar select Scan followed by Quick Scan. 3. Enter the desired Start angle, End angle, Step, Dwell (count time) in the dialog box. 4. If the alignment marks on the goniometer are reasonably aligned (Section 1.3.1), then select a 2 scan range from 67º and ending at 72º or narrower (if you feel lucky) and a Step Size of .0.04 for a quick check to locate the Si (004) XRD peak (69.13º). Once, the peak is located, you are encouraged to narrow your scan range and reduce the step size. Recommend a Dwell time of 1.0 second for the Quick Scan mode. 5. Choose and select Axis: Both axis to ensure both and 2 drives are coupled.

1.3.2.2 Perform a Quick Scan to Check Alignment 1. Power on the Rigaku XRD generator and open the shutter per section 1.1. 2. Select OK on the Quick Scan dialog box to commence the scan. 3. If the plot produces the two K 1 and K 2 peaks, then place the mouse cursor arrow at the K1 peak and a small box will display the peak counts and 2 angle. 4. If the K 1 peak is at 69.13º +/-0.02º, then proceed to Section 1.4 to run scans of your sample(s), otherwise note the 2 value and proceed to Section 1.3.2.3. 5. If a plot of the K 1 and K 2 peaks are not found, then repeat 1.3.2.2 over a wider range. 1.3.2.3 Optimize the /2 Goniometer Alignment 1. Return to the Quick Scan dialog box. (1.3.2.1.2) to rock only the sample goniometer drive by selecting Axis: Theta axis. 2. Enter the maxima value in the Detector window box. acquired in step 1.3.2.2.6 3. Enter the scan range for . Caution: these values are one-half of 2 values. 4. Press OK and then again after confirming the displayed values entered. Step 1.3.2.3 fixes the detector position at the maxima angle value entered in Step 3, which is then followed by scanning the sample about over the range of values entered.

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5.

Note the maxima angular value of the first broad peak (left peak) corresponding to K 1. If the individual K 1 and K 2 peaks are indistinguishable, then choose the maxima value. 6. Open MDI Databox/Drive tab and enter the maxima angular value in the Drive to: box 7. Select Axis: Theta axis and click on Go. Aligning to the angular position corresponding to the maxima found above optimizes at precisely one-half of the 2 position of Detector. Thus, with the Detector at its 2 maxima, we have optimized the sample rotation to the maximum. We now need to calibrate the and 2 goniometer drives for the correct angular values for Si(100) so the goniometer is in agreement with the Datascan4 software. 1.3.2.4 Calibrating the /2 Goniometer Positions 1. 2. 3. 4. From the DataScan4 menu bar, choose Control and MDI Databox and the Drive tab. Enter the correct value of 69.13 degrees for Si(004) for the Detector and click on SET. Enter the correct value of 34.565 degrees for Theta and click on SET. Repeat 1.3.2.2 to confirm the /2 is optimized and the goniometer is calibrated.

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1.4 Recording and Saving XRD Scans

1.4.1 Scan Acquisition

1. Once the XRD instrument is properly set up per Section 1.3, place your specimen holder in the XRD instrument per Section 1.2 and if necessary power on the instrument per Section 1.1. and also if necessary double click "DataScan4" icon on the desktop 2. For Single Scans you may use Quick Scan: a. Select Scan from menu bar followed by clicking on Quick Scan option on the drop down menu. b. Enter the desired Start angle, End angle, Step, Dwell (count time) c. Select OK and again after confirming the parameters. d. For Quick Scan mode, once the last scan is complete goniometer must be manually

parked using the procedure in Section 1.5.2.

Quick Scan may be used to quickly enter run parameters in a "Scan Range" window and collect data. However at the end of a Quick scan data collection, the user must save the file (in .MDI format) with a File-Save command or the scan data will be lost when you quit the program. 3.For Single or Multiple Scans use Routine Scan: see figure on next page a. Select Scan from menu bar followed by Routine Scan on the drop down menu. b. In the Setup Scan window select New Scan Job (upper left blank paper icon) followed by New Range or place the cursor in the New Scan Job window and right click New, c. Enter desired Start angle, End angle, Step, Dwell (count time) in the New Scan Range dialog box, followed by OK. d. In Filename window enter the file name for your scan followed by OK. e. Check the list of scans in the Setup Scans window and make sure only your Routine Scan is checked and all other scans are unchecked. f. Select Start g. Once a Routine Scan is complete, the goniometer will typically park at 10o automatically. If not, then for the last scan manually parked the goniometer using the procedure in Section 1.5.2.. Routine Scan uses a setup table to configure scan parameters and automatically saves data. It provides more control, allows re-use of saved setup routines, and lets the user enter additional sample information into the data file. Routine scan is recommended for data collection.

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1.4.2 Saving Scan Data Routine Scan will automatically save data as "(filename).ASC" file which can be read by Excel, Origin, NotePad etc. without file conversion. Files are saved at the "DataScan4 data" folder; there is a shortcut icon on the desktop. All ranges of scan data will be saved in one single file. 1. To save as *.txt file: "View" window "Save" 2. To save as *.mdi file: "File" "Data points" "Save Data As" "File" at the "Scan Data"

Scan files may be copied to a USB memory stick using one of the USB ports at the rear of the PC.

1.5 Shutting Down the Instrument

1. Remove your sample. 2. Check the goniometer /2 alignment per Section 1.4 using the Si(004) sample provided. 3. Park the goniometer at 10o: a. From Datascan4 menu bar select: Control and MDI Databox and the Drive tab.

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b. Enter 10 in the Drive to: box and select Both Axis and then execute the park by selecting Go. c. Close the window after the goniometer stops. This is done as a matter of courtesy, and also in the even of a power interruption, the goniometer is in the correct position and the Databox can be reset to the correct angle.

4. Exit "DataScan4" and log off 5. Turn off the XRD instrument. Slowly turn down the current and voltage. First decrease the current then the voltage to their minimum values. This should be done slowly but not as slowly as turning them up, 1 to 2 minutes. 6. Depress the X-ray OFF button (white lever switch). 7. Check the hour meter Record the hour meter value in the log book and subtract the starting number to obtain total hours used. Record any other applicable comments regarding the instrument. 8. Depress the instrument OFF button (red lever switch). 9. Remove your specimen and complete the log book. 10. Clean up area after yourself.

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Chapter 2: XRD Data

2.1 Accessing the JCPDS Powder Diffraction Files

Accessing the JCPDS file program The JCPDS files are the international collection of tabulated data on x-ray powder diffraction information of the known and characterized material phases. These files are stored on a Windows based PC in 3066 EB1. They can be accessed by clicking on the `Shortcut to PC-PDF. It will ask you to press any key to continue. After doing so it will give you a list of options. Choose 1<CR> for to retrieve a JCPDS file. The details regarding the use of the other options may be obtained from the JCPDS manual. Obtaining a JCPDS file At this point a JCPDS file may be accessed in one of three ways. · By number Typing JCPDS file number (incl. the dash, e.g. 2-39941) · By three strongest lines Type in the d-spacing of the three strongest lines offset by commas or spaces, e.g. 3.541 2.695 1.995 or 3.541, 2.695, 1.995. You may specify a search range by entering two numbers for each separated by only a dash, e.g. 3.540-3.544 2.6922.698 1.991-2.000. Note that it may take the computer a long time to display all of the possible results if the range is relatively large. · By name Type in either the mineral name, e.g. quartz or the chemical name e.g. silicon oxide. Use the most generic chemical name for the material, for instance silicon oxide for quartz not silicon dioxide or barium titanium oxide not barium titanate. Follow your entry with a <CR>. Displaying a JCPDS file A diffraction file can be displayed from a list of one or more of the files by choosing it either by typing the number of the choice followed by <CR> or by highlighting it with the up and down arrows and hitting <CR>. The Page up and Page down keys can be used to scroll up or down through the file. Items you should take note of when comparing them to other data is: quality rating (e.g. * very good, i incomplete, etc.) composition,

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thermodynamical conditions (e.g. pressure, temperature, etc.), radiation, and date of reference among other special notes. Peak position may be displayed in terms of dspace by typing d or 2 theta by typing 2. Hit the escape key to return to the file menu. Hit escape again to search for a new material system. Printing a JCPDS file The files chosen may be printed by pressing the F2 key. Again first be sure that the printer is on-line and the paper is in the correct position. Exiting JCPDS files Hit the escape key until you have reached the first menu screen. The last option will be to type 0 for exiting the program. After doing this you will be back in DOS, however, you will notice a warning message. I recommend that you hit the red reset button immediately before you forget. You can do this even while running a scan since the Databox is controlling the goniometer.

2.2 Ghost peaks

One of the most common mistakes made particularly by those who work with thin films mounted on single crystal wafers of highly covalent materials, e.g. Si, GaAs, is to index a ghost peak as a film peak. Ghost peaks arise from three sources. The most obvious ghost peak occurs as the result of some of the beam diffracting with the holder material or one of the slits that are improperly inserted. The solution to this should be immediately obvious. In the second case radiation of wavelengths other than CuK, occurs from the Bremsstrahlung or breaking radiation that is produced in the target material as the electrons that are hitting the target decelerate. This radiation should not be detected if the monochromator and the slits surrounding the monochromator are in the correct positions. The third is more subtle but fairly common and extremely important to the thin film community. In this case, peaks arise that are forbidden by destructive interference according to structure factor calculations. This is observed in the case of Si (100) standard for the 200 ghost peak at approximately 32.9°. Since electrons in covalently bonded semiconductors are located in a lobe-type fashion about the atom that is not spherically symmetric, the assumption that the electrons are located at the exact atomic locations is incorrect. For precise calculations of the x-ray diffraction pattern, quantum mechanics is necessary.

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Chapter 3: Appendix

3.1 Instrument Specifications

The diffractometer The x-ray diffractometer is a D/Max A series x-ray and built by Rigaku Inc. It contains a Cu anode tube (weighted average = 1.5418Å) and a graphite monochromator which passes only the CuK1 and CuK2 radiation through the slit. In 1990 it was fitted with a computer interface unit known as the Databox. The Databox The Radix Databox is located inside of the old goniometer controller. The unit is designed to count the pulses from the Rigaku pulse height analyzer and drive the x-ray goniometer with the existing stepper motors. It stores a maximum of 32K data points and communicates with the IBM PC through a program known as Datascan4. The software The powder diffraction files program helps you to identify relevant cards by chemical name, mineral name, other three strongest lines. It is the 1989 version PDF-1 and has 53,000 cards sorted in sets of 1-39.

3.2 Theta/2-Theta alignment using TALK

3.2.1 TALK Commands

Turn on the computer and activate the TALK icon. The computer should go directly in the Databox talk program and say "hit any key to continue". (Hit any key except for escape.). Go to edit mode Press e <CR>. You may have to hit this twice if the computer first says `Exit to monitor'. Once you are in `edit mode' be sure that sequence #1 is current. If it is not, then press p<CR> for the previous sequence or n<CR> for the next sequence. Be sure that sequence #2 is undefined, unless you plan to do multiple scans of the same sample. If other sequences are not undefined you can undefine then by making them current (p or n) and then typing u<CR> for undefine sequence. Now for sequence #l you can set the scanning

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range i<CR> for initial two theta angle and f<CR> for final two theta angle, the step size. s<CR> (remember that the goniometer moves in steps, not continuously), and the count time in seconds c<CR>. It is recommended that if you are pretty sure that you will not be missing any important peaks, if possible, start after 25° so you will miss the Bremsstrahlung (breaking radiation). Do not make the final angle greater than 125° so that the tube will not be damaged. Typically 0.05° step size and a count time of 2 or 3 seconds is satisfactory most scans. Go to monitor mode Type e<CR> for the `Exit to monitor' mode, then type s for the `scan mode'. Do not immediately press <CR>. It will ask for a title. You may put in whatever title you want with whatever keys you want. Next look to be sure that the shutter #2 light is on indicating that it is open. Now you may hit <CR>. Note that if you do not specify a title it will use the previous title by default. Do not touch the keyboard until the goniometer has come to the initial plot angle or it may lose its settings. Graphing data does not work for TALK operating in Windows. Terminating a scan To terminate a scan before it is completed type t<CR>.

3.2.2. Theta/2-Theta Alignment Using TALK

Place the Si(004) single crystal standard in the goniometer holder Place the Si single crystal standard into the sample chamber, with the shiny Si side facing towards the door. The standard is a (100) silicon wafer which has peaks at CuK1 = 69.13° 2-theta and CuK2 = 69.33° 2-theta, with the 69.13° peak being the largest. The CuK1 peak should be used to check the alignment. Set up a scan to check the peak position If you suspect that the alignment is not too far off use: i = 69, f = 70, s = 0.01, c = 1. You can terminate the scan early with the command t<CR>, once you locate the peak. Go to the peak position First type c<CR> for calibrate mode then type g for go to followed by the two theta angle in degrees (e.g. 60.09°) of the two theta angle where there was the maximum number of counts (intensity). If you do not remember the angle type p<CR> for plot and hit the space bar or <CR> to start and stop the scrolling. Type e then to exit this.

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Set 2-Theta to 69.13° Type a for angle and type 69.13. Uncouple the axes Now that the detector and monochromator are at the position of the peak, it is necessary to run a rocking curve of the crystal. This is to optimize the orientation of the sample with respect to the x-ray beam. This is done by typing u for uncouple axis followed by 2<CR> for 2 theta. Rerun the scan You may use the scan you used earlier (type e<CR> p<CR> and then e<CR> s<CR>), however, since theta tends to be off by more, perhaps start at i = 68°. Again the goal is to locate the peak position. Of course if you think you missed the peak terminate the scan and reset the initial and/or final angles and rerun it. Align theta Once again the procedure is: c<CR> g<angle of peak> Couple the axes and redefine theta This is a very important step which people seem to forget. Type u and then n<CR> for neither. Then type a for angle and type 69.13. Again rerun the scan Now you are checking your work (type e<CR> p<CR> and then e<CR> s<CR>). If the alignment was not off by much you should be within 0.01° and 40,000+ counts/sec with the standard slits. If your alignment was not so good to start with, you may have to reiterate the entire procedure 1 or 2 more times. If your alignment is good then you can put your own sample in now and start your own scan.

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Chapter 4: Troubleshooting

These are some of the most common problems and solutions. If the solutions do not work for a particular problem or a different problem arises please contact the TA.

4.1 Instrument Problems

1) Symptom: Alarm sounds and stays on when the power button is pressed. Problem: Insufficient water flow through the tube head. Action: Check to be sure the Haskris water heat exchanger is on. Do not run the machine without sufficient water flow; it will destroy the x-ray tube. 2) Symptom: The X-ray ready light does not come on and the X-ray generator will not come on Problem: Safety interlocks are activated. Action: Check to be sure the current and voltage knobs are at their lowest settings and the doors are closed (the center door must be in the center position). 3) Symptom: Machine shuts off after operating for a while. Problem: Chiller is overheating. Action: Check to be sure that the building chilled water lines are open. 4) Symptom: Machine shuts off while turning up or turning down the current or voltage. Problem: Either the current was increased before the voltage (or vice-versa) or the settings were turned up too quickly. Action: If turning on the machine, turn the voltage to their lowest settings then press the x-ray on switch and try again the correct way (see Chpt.1) If turning off, turn the voltage to their lowest settings then continue with the shut down procedure. 5) Symptom: Insufficient counts from standard after alignment. a) Problem: Step size is too large Action: Check alignment procedure and step size (Section 1.3) b) Problem: Incorrect slits Action: Use standard slits in Section 1.2

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6) Symptom: No counts above background. a) Problem: Theta misaligned Action: Realign using procedure in Section 1.3 b) Problem: 2 theta misaligned Action: If grossly misaligned, use vernier scale on goniometer to redefine the angle in calibrate mode in TALK, then realign using the Si standard and the procedure in Section 1.3. 7) Symptom: Zero counts Problem: Shutter closed and/or wrong shutter open Action: Open shutter #2 only 8) Symptom: Databox has been off, and says it needs recalibration when using TALK. Action1: Close TALK and activate Datascan4 which automatically initialize Databox Action2: Type "A" and center present 2 theta value, "S", enter 500 steps/degrees and"M", enter max 1500

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Chapter 1: Collecting Data

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