Software Manual Section 10

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Setup 1 for Isotopic Measurements
	Introduction In order to keep the 'Isotope' measurement program as flexible as possible (it can be used for much more than just istotopes), there are many more control options than would fit into one window. The controls are therefore distributed over several "Iso Setup" windows. The function of this first window is to define a list of masses that are to be measured.
	Clear All By default, this window will initially load the last setup that was used for isotopic measurements. To start with an empty mass list, click here.
	Load If you don't want to start from scratch, you can load a previously saved setup file with this button. Over time, we should collect a small library of setup files for all the standard measurement conditions (e.g. C, O and Si isotopes). There is another important way to load a previous setup: You click here and simply select any data file with the results from a previous measurement and the setups used for that measurement are automatically loaded. This way, the setup information does not get lost, even if you did not save an individual setup file earlier. (This of course only works with data files of the 'new' format; see Section 12 for a discussion of the different data file formats.) Note: This option is not yet implemented (as of 6/2000).
	File Name Display The name of the setup file that has been loaded is displayed here. Note that the text displayed here changes from the file name to "-not saved-" the instant you make any changes to the setup.
	Sort Order Note that the mass list displayed here is self-sorting. There is no need to enter the species in ascending mass order.
	Select from Periodic Table If you do want to start from scratch with an empty mass list or you want to add a mass to the existing list, click here. This will get you to the Periodic Table that has been discussed in detail in Section 5. There you can select an atomic or a molecular species that will then be entered into the mass list here. Click this button for each species you want to add.
	Enter Masses Manually To enter masses manually, select the first empty text box under "Name" by clicking into it. This place is marked in the figure on the left with a red '*'. Then enter a species to be added and press enter. The entry will then be evalutated and sorted into the list of previous entries. Which kinds of entries are valid is discussed below. To delete an entry, simply select its entire name, delete it and then press enter. All list entries below will be moved up.
	Valid Entries Here is a list of different kinds of valid entries for the species name. Only when a valid entry is made, the atomic mass can automatically be calculated. Entering this... will be converted to... and means... c 12C 12C the most abundant isotope will be selected by default 13c 13C 13C c c 12C 12C 12C2 molecule h c 15n 1H 12C 15N molecule c2+ 12C 2+ 12C++ (doubly charged) left edge "left edge" Special mass. Must enter amu-value manually. cn "cn" Should have been 'c n' (with space in-between) for 12C 14N molecule. Name wasn't recognized and therefore interpreted as special mass "cn". To correct, remove quotes and add space.
	Mass The atomic mass (in amu) will automatically be calculated for all atomic and molecular species that can be recognized. It is not possible to manually change the mass value for those valid species entries. A "??" in the mass column indicates a special mass (see above). Here, a mass value has to be entered manually.
	B-Field The corresponding B-Field value will be calculated for all masses. Here, a manual entry is not possible.
	Mass Difference If you want the program to center on a certain mass peak, but then perform the actual measurement at a certain distance from the center, enter the difference (in amu) here. This can be useful for measuring peak tails. By default this value is zero.
	Centering Automatic peak centering will usually be performed by finding both the left and the right edge of the peak first. This is the default, which is indicted by an empty box in the "Cent." column. If you want to center only on the left or the right edge, click here and select "L" or "R" from the pull-down menu.
	Detector By default, any mass in the list will be measured with the electron multiplier ("EM") detector. To force measurement with the Faraday cup, click in the "Det." column and select "FC" from the pull-down menu.
	Ratio Oops, this column currently has no function. Defining isotopic ratios to be calculated has been moved to IsoSetup 2.
	Time Enter the desired counting time (in seconds) for each mass in this column. The default value is 1 second.
	Wait This is the time (in seconds) before the measurement of this mass that is allocated to the changing of the B-Field. Basically, there should be a value here that depends only on the size of the B-Field change.
	Minimize Wait Time After all masses are entered, click on this button. It calculates the 'optimum' wait times between masses and changes the 'Wait' fields accordingly. You can always change these wait times to higher values, but it is not recommended to choose wait times shorter than the ones calculated here.
	Scroll Buttons To scroll through a long list of masses, use these buttons. The single arrows move up or down by one line and the double arrows move by 10 lines. There is no upper limit to the number of masses that can be added to the list.
	Show MRP Pressing the button changes the right half of the display table. A new column labelled "m/dm" appears and shows the mass resolving power needed to separate neighboring mass peaks. Note that the numbers in this column are positioned 'between' rows to indicate that the mass resolution shown is needed for the separation of the upper and the lower row. In the example below, a mass resolving power of 5443 is needed to separate the peaks at 26.00307 and 26.00785. The label "low" indicates that these peaks are separated even at the lowest possible mass resolution (300).
	Abort ISO Stops IsoSetup and closes this window.
	Continue Closes this window and goes to IsoSetup 2 for the second part of the measurement setup.

FJ Stadermann	Back to Top	Next Section