Research Group

of Klaus Boldt


Insensitive for OS X


Insensitive (Incredible Nuclear Spin EvolutioN SImulation Tool Intended for Visual Education) is a simulation of the NMR experiment written for educational use. The application allows to interact with every step from spin precession to Fourier transformation and processing of acquired 1D and 2D spectra. The software runs on Mac OS X 10.6 and above. A a subset of the simulation capabilities are also available for the iPhone, iPad, and iPod touch.

When learning or teaching the physics behind the nuclear magnetic resonance (NMR) experiment one has to deal with several quantum mechanical models that become more and more abstract as the scholar advances in the subject. Most classes start with the relatively simple energy level and vector model, which inevitably fails with the simplest two-dimensional techniques such as 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 visualises all three models.

Insensitive comes with a tutorial that explains the concepts of modern NMR and includes a step-by-step analysis of many pulse programmes. While other NMR applications simulate a virtual spectrometer (VSNMR, MestRe-S), are only available as part of commercial NMR spectrometer software suites (Bruker TopSpin 3.0) or already require deep knowledge of NMR theory (SpinDrops, Spinach) or a programming language (Gamma, mPackages) Insensitive focuses on the visualization of textbook NMR theory.

Insensitive is intended for education or self education in NMR at an intermediate level. It does not teach how to interpret spectra, and it does not try to teach or implement state-of-the-art simulation algorithms. A basic understanding of quantum mechanics (or the willingness to tackle the field) is recommended. 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 and Understanding NMR Spectroscopy by James Keeler as a companions for using Insensitive.

A paper on Insensitive has been published in Concepts in Magnetic Resonance Part A. If you use the program or parts thereof in publications or presentations, please cite K. Boldt, Conc. Magn. Reson., 2011, 38A (2), 17-24. The legacy version (0.9.5) discussed in the paper can be downloaded here.

Concerning Insensitive for Windows

I have been approached by several users to release Insensitive for Windows or Linux. I would love to support other platforms, but since Insensitive has been written in Objective-C and now includes about 20.000 lines of code this is a big project. There are two possible toolkits to port Insensitive, GNUstep and The Cocotron. Cocotron seems to be the choice for user-friendliness, but Apple's Accelerate framework for matrix algebra and FFT (BLAS, LAPACK and vDSP) is not yet easily available. At the moment I favour a platform-independent approach that would include a complete rewrite using Qt or WxWidgets for the user interface. Help pushing this project forward is highly appreciated! If you have interest as well as experience with coding in Objective-C and/or C++ as well as understanding of NMR theory please contact Klaus Boldt.

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