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Author: Klaus Boldt
License: MIT

Insensitive is a software tool to simulate and visualize the NMR experiment. It is intended for educational purposes at an intermediate level and focuses on the visualization of textbook NMR theory.

When learning or teaching NMR one has to deal mainly with three quantum mechanical models. Most classes start with the relatively simple vector model, which inevitably fails with the simplest two-dimensional techniques like COSY. A more complete model is the product operator formalism, which in turn is based on the density matrix approach of statistical quantum mechanics.

This software simulates the NMR experiment by visualizing all three models mentioned above. The user can interact with every step of the experiment, from the first pulse to the phase correction of the acquired spectrum after Fourier transformation.

Insensitive (Incredible Nuclear Spin EvolutioN SImulation Tool Intended for Visual Education) comes with a tutorial that explains the concepts of modern NMR and includes a step-by-step analysis of many pulse programs. Although the tutorial introduces the basic concepts it is not intended as a textbook of its own. The author recommends the textbook Spin Dynamics by Malcolm H. Levitt as a companion for using Insensitive.

Features include:
  • Pulses with arbitrary flip angle and phase.
  • Selective hard and soft pulses and off-resonance effects.
  • Up to four different spins of type I or S.
  • Graphical setup of the spin system.
  • Animated vector model.
  • Colour-coded vectors.
  • Automatic calculation of product operators in cartesian or spherical basis.
  • Coloured observable matrix elements.
  • Energy level diagrams.
  • Setup of product operators in the Matrix Editor.
  • Weak and strong scalar coupling.
  • Decoupling and spin locking.
  • Simple exponential or dipolar relaxation.
  • Recoding, editing and playing of pulse sequences.
  • 1D and 2D Acquisition of the FID with quadrature detection and complex Fourier transformation.
  • Real time phase correction.
  • Selection of apodization and line narrowing functions.
  • Interaction with every step of the time evolution.
  • Phase cycling.
  • States and TPPI methods for 2D spectrum acquisition.
  • Comprehensive tutorial.

Also available for the iPhone.

This software is in its beta stages and the author appreciates any feedback, comments and bug-reports.


  • K. Boldt, Conc. Magn. Reson. 2011, 38A (2), 17-24.
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