Chemical Shift PPM to Hz Converter
Invert a signed chemical shift into a frequency offset using reference frequency in MHz; this is distinct from existing sample/reference frequency-to-ppm tools.
Description
Parts-per-million chemical shift describes a relative frequency difference.
Parts-per-million chemical shift describes a relative frequency difference. Multiplying ppm by a reference in MHz gives the offset directly in Hz.
The tool returns offsetHz (offset hz). Input measurements and model parameters are supplied by the caller; the tool computes the stated summary rather than acquiring those measurements.
When to use Chemical Shift PPM to Hz Converter
Use Chemical Shift PPM to Hz Converter when you already have chemicalShiftPpm, referenceFrequencyMHz and want offsetHz. This is useful for checking a supplied calculation, documenting a measurement convention, or comparing observations prepared on the same basis.
How to use Chemical Shift PPM to Hz Converter and understand its results
- Enter chemicalShiftPpm, referenceFrequencyMHz using the field table below. Match the units, ordering and data boundaries described in the calculation.
- Run the tool after checking the stated bounds and matching paired observations or categories. A malformed request gives a tool error rather than a usable measurement.
- Read offsetHz. Use the calculation and interpretation below to distinguish amounts, ratios, signs and decision flags where applicable.
- Review the supplied parameters and assumptions before using the result in a report or comparing it with another observation.
| Input field | Meaning | Value type and bounds | Requirement |
|---|---|---|---|
| chemicalShiftPpm | Chemical shift ppm | number | Required |
| referenceFrequencyMHz | Reference frequency m hz | number | Required |
Require a positive reference frequency and preserve the sign of the supplied shift.
offsetHz = chemicalShiftPpm×referenceFrequencyMHz The symbols refer to the supplied quantities or generated values described above; unit conversions and comparison boundaries follow the stated implementation.
{
"input": {
"chemicalShiftPpm": -3.5,
"referenceFrequencyMHz": 100
},
"output": {
"offsetHz": -350
}
}Limitations and assumptions
The reference and chemical shift must use the intended convention; no molecular assignment or spectrum is read.
Numerical inputs must be finite. The tool checks its declared input shape and calculation constraints; those checks do not verify the quality, calibration or representativeness of the supplied observations.
Alternative or Complementary methods
Chemical Shift Artifact Pixels: Estimate signed frequency-encoding chemical-shift displacement using supplied shift, reference frequency and pixel bandwidth; direction depends on readout polarity. B0 Inhomogeneity PPM: Summarize a measured B0 offset map in ppm with peak-to-peak and RMS about the frequency reference, not a fitted shim solution.
Methodological background: RAD229: MRI signal and sequence lecture notes.1
References
-
RAD229: MRI signal and sequence lecture notes — Brian Hargreaves and colleagues, Stanford University
Similar or alternative tools
- Chemical Shift Artifact Pixels
Estimate signed frequency-encoding chemical-shift displacement using supplied shift, reference frequency and pixel bandwidth; direction depends on readout polarity.
- B0 Inhomogeneity PPM
Summarize a measured B0 offset map in ppm with peak-to-peak and RMS about the frequency reference, not a fitted shim solution.