Method for accurate measurements of nuclear-spin optical rotation for applications in correlated optical-NMR spectroscopy

[Display omitted] •A low-cost setup for Nuclear Spin Optical Rotation (NSOR) measurements is developed.•A detailed analysis of geometric effects affecting NSOR measurements is presented.•NSOR is measured with improved signal-to-noise ratio and accuracy.•The use of NSOR as an alternative NMR detection methodology is discussed. The nuclear-spin optical rotation (NSOR) effect recently attracted much attention due to potential applications in combined optical-NMR spectroscopy and imaging. Currently, the main problem with applications of NSOR is low SNR and accuracy of measurements. In this work we demonstrate a new method for data acquisition and analysis based on a low-power laser and an emphasis on software based processing. This method significantly reduces cost and is suitable for application in most NMR spectroscopy laboratories for exploration of the NSOR effect. Despite the use of low laser power, SNR can be substantially improved with fairly simple strategies including the use of short wavelength and a multi-pass optical cell with in-flow pre-polarization in a 7T magnet. Under these conditions, we observed that NSOR signal can be detected in less than 1min and discuss strategies for further improvement of signal. With higher SNR than previously reported, NSOR constants can be extracted with improved accuracy. On the example of water, we obtained measurements at a level of accuracy of 5%. We include a detailed theoretical analysis of the geometrical factors of the experiment, which is required for accurate quantification of NSOR. This discussion is particularly important for relatively short detection cells, which will be necessary to use in spectroscopy or imaging applications that impose geometrical constraints.