title: Time domain para hydrogen induced polarization.
abstract: Para hydrogen induced polarization (PHIP) is a powerful hyperpolarization technique, which increases the NMR sensitivity by several orders of magnitude. However the hyperpolarized signal is created as an anti-phase signal, which necessitates high magnetic field homogeneity and spectral resolution in the conventional PHIP schemes. This hampers the application of PHIP enhancement in many fields, as for example in food science, materials science or MRI, where low B(0)-fields or low B(0)-homogeneity do decrease spectral resolution, leading to potential extinction if in-phase and anti-phase hyperpolarization signals cannot be resolved. Herein, we demonstrate that the echo sequence (45°-τ-180°-τ) enables the acquisition of low resolution PHIP enhanced liquid state NMR signals of phenylpropiolic acid derivatives and phenylacetylene at a low cost low-resolution 0.54 T spectrometer. As low field TD-spectrometers are commonly used in industry or biomedicine for the relaxometry of oil-water mixtures, food, nano-particles, or other systems, we compare two variants of para-hydrogen induced polarization with data-evaluation in the time domain (TD-PHIP). In both TD-ALTADENA and the TD-PASADENA strong spin echoes could be detected under conditions when usually no anti-phase signals can be measured due to the lack of resolution. The results suggest that the time-domain detection of PHIP-enhanced signals opens up new application areas for low-field PHIP-hyperpolarization, such as non-invasive compound detection or new contrast agents and biomarkers in low-field Magnetic Resonance Imaging (MRI). Finally, solid-state NMR calculations are presented, which show that the solid echo (90y-τ-90x-τ) version of the TD-ALTADENA experiment is able to convert up to 10% of the PHIP signal into visible magnetization.
authors.affiliation: Institute of Physical Chemistry, Technical University Darmstadt, Petersenstrasse 22, D-64287 Darmstadt, Germany.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Ratajczyk
authors.forename: Torsten
authors.initials: T
authors.lastname: Gutmann
authors.forename: Sonja
authors.initials: S
authors.lastname: Dillenberger
authors.forename: Safaa
authors.initials: S
authors.lastname: Abdulhussaein
authors.forename: Jaroslaw
authors.initials: J
authors.lastname: Frydel
authors.forename: Hergen
authors.initials: H
authors.lastname: Breitzke
authors.forename: Ute
authors.initials: U
authors.lastname: Bommerich
authors.forename: Thomas
authors.initials: T
authors.lastname: Trantzschel
authors.forename: Johannes
authors.initials: J
authors.lastname: Bernarding
authors.forename: Pieter C M M
authors.initials: PC
authors.lastname: Magusin
authors.forename: Gerd
authors.initials: G
authors.lastname: Buntkowsky
mesh_terms: D000114:Acetylene / Q000031:analogs & derivatives / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000191:economics / Q000379:methods*; D010666:Phenylpropionates / Q000737:chemistry; D013997:Time Factors
chemical_list: D010666:Phenylpropionates; C044736:phenylacetylene; C019521:phenylpropiolic acid; D006859:Hydrogen; D000114:Acetylene