Abstract

This thesis focuses on the developement of novel ultrafast Laplace NMR (UF LNMR) methods. LNMR covers relaxation and diffusion measurements, which provide detailed information about dynamics of molecules. Ultrafast LNMR is based on spatial encoding of multidimensional data, which has been earlier been exploited in ultrafast NMR spectroscopy. The method makes it possible to collect multidimensional data in a single scan, shortening experiment time by one to four orders of magnitude. Furthermore, single-scan approach enables use of modern hyperpolarization methods, such as dynamic nuclear polarization (DNP), parahydrogen induced polarization (PHIP) and spin-exchange optical pumping (SEOP), to boost the sensitivity of the experiments by orders of magnitude. Therefore, the method provides means to study fast molecular processes in real-time, with high sensitivity.

In the first part of the thesis work we introduce a novel single scan, spin echo based diffusion experiment (UF PGSE), and compare it to already established single scan, stimulated echo based method (UF PGSTE). We show that the UF PGSE method removes artefacts, which appear in UF PGSTE data. We represent also a thorough theoretical analysis which justifies the feasibility of the method. The analysis reveals also that a conventional exponential fit results in a small overestimation of diffusion coefficient.

The second part comprises two scientific articles dealing with a novel two-dimensional D − T₂correlation experiment. We demonstrate the feasibility of the method in chemical analysis and in the investigation of porous materials. In addition we prove that the single-scan approach really makes it possible to exploit nuclear spin hyperpolarization using three different techniques: PHIP, dissolution DNP and SEOP. We show that, with hyperpolarization, single-scan experiments became feasible even with low sensitivity heteronuclei.

In the last part, we introduce an ultrafast exchange experiment. It is based on diffusion contrast and called ultrafast diffusion exchange spectroscopy (UF DEXSY). In traditional DEXSY experiment, data of both indirect and direct dimension are collected point-by-point in repeated experiment, while in UF DEXSY whole data is measured in a single scan. This leads to significant, up to four orders of magnitude, reduction of experiment time. Because UF DEXSY provides opportunity to boost the sensitivity of the experiment by orders of magnitude by hyperpolarization, it offers unprecedented opportunities for efficient and high sensitivity analysis of important molecular exchange processes such as cellular metabolism, catalysis and chemical reactions.

Osajulkaisut / Original papers

Osajulkaisut eivät sisälly väitöskirjan elektroniseen versioon / Original papers are not included in the electronic version of the dissertation.

1. Ahola, S., Mankinen, O., & Telkki, V.-V. (2016). Ultrafast NMR diffusion measurements exploiting chirp spin echoes. Magnetic Resonance in Chemistry, 55(4), 341–347. https://doi.org/10.1002/mrc.4540

   Rinnakkaistallennettu versio / Self-archived version

2. Ahola, S., Zhivonitko, V. V., Mankinen, O., Zhang, G., Kantola, A. M., Chen, H.-Y., … Telkki, V.-V. (2015). Ultrafast multidimensional Laplace NMR for a rapid and sensitive chemical analysis. Nature Communications, 6(1). https://doi.org/10.1038/ncomms9363

   Rinnakkaistallennettu versio / Self-archived version

3. Mankinen, O., Hollenbach, J., Ahola, S., Matysik, J., & Telkki, V.-V. (2018). Ultrafast Laplace NMR with hyperpolarized xenon gas. Microporous and Mesoporous Materials, 269, 75–78. https://doi.org/10.1016/j.micromeso.2017.10.024

   Rinnakkaistallennettu versio / Self-archived version

4. Mankinen, O., Zhivonitko, V. V., Selent, A., Mailhiot, S., Komulainen, S., Prisle, N. L., … Telkki, V.-V. (2020) Ultrafast diffusion exchange NMR. Manuscript submitted for publication. https://doi.org/10.1038/s41467-020-17079-7

   Rinnakkaistallennettu versio / Self-archived version