Adding the Projections around a 2-D Plot
A 2-D plot becomes easier to interpret when the corresponding 1-D spectra are displayed around its borders. When available, independently acquired 1-D spectra provide the best projections and are called external projections. Otherwise, projections can be generated directly from the 2-D data; these are called internal projections.
How to Add External Projections:
- Open the 1-D spectra to add. In the case of a homonuclear correlation 2-D experiment, a single spectrum is sufficient for both projections.
- Return to the main plot and choose Format > Overlay.
- You will see the list of the other windows. Check the box next to each spectrum that should be used as a projection.
- Adjust the amplification factor reported in the last column. You can press Fit Intensity for an automatic adjustment, use the small arrows, or enter a numerical value. Additional controls for horizontal and vertical projections are described below.
- Close the dialog.
- By default, projections appear on the borders that do not contain frequency scales. To move a projection to a different border, change the position of the scales through Format > Axes & Scales, click Units, etc.
- When the dialog is closed, you can still change the relative amplification of a projection with the mouse wheel (move the mouse over the projection to amplify). If you have no scroll wheel, use the keys * and /. The latter shortcuts, however, only work with the last projection of each document.
- You can drag the four borders with the mouse to allocate more or less space, around the plot, for the projections.
- You can insert an empty space between the main plot and the projection: open the iNMR Settings, reach the second panel (Display) and set the parameter called “Gap under the Projections”.
With an identical mechanism you can combine two or more 2-D spectra, perfectly aligned, in the same plot. For example: a COSY, a TOCSY and a NOESY of the same sample. Projections remain aligned automatically when spectra are recalibrated, rescaled or reprocessed.
Internal Projections
You can generate an internal projection with the command Collapse.
Doing it manually is a time-consuming operation. It is convenient to use the ready scripts
“projxy” and “projxyplus” available in the
web library.
How the Projections are Amplified
The Overlay Manager provides two levels of amplification. The value shown in the last column of the table belongs to the individual overlay and affects every projection generated from that spectrum.
In addition, the box Amplify the Projections contains two other factors: one for horizontal projections and one for vertical projections. These factors are applied on top of the overlay amplification. After changing either value in the box, press the Return key or click Apply to update the display.