The University of Southampton
University of Southampton Institutional Repository

Excitation of singlet-triplet coherences in pairs of nearly-equivalent spins

Excitation of singlet-triplet coherences in pairs of nearly-equivalent spins
Excitation of singlet-triplet coherences in pairs of nearly-equivalent spins
We present approaches for an efficient excitation of singlet–triplet coherences in pairs of nearly-equivalent spins. Standard Nuclear Magnetic Resonance (NMR) pulse sequences do not excite these coherences at all or with very low efficiency. The single quantum singlet–triplet coherences, here termed the outer singlet–triplet coherences, correspond to lines of low intensity in the NMR spectrum of a strongly-coupled spin pair (they are sometimes referred to as “forbidden transitions”), whereas the zero-quantum coherences, here termed the inner singlet–triplet coherences, do not have a direct spectral manifestation. In the present study, we investigated singlet–triplet coherences in a pair of nearly-equivalent carbon spins of the 13C-isotopomer of a specially designed naphthalene derivative with optimized relaxation properties. We propose and compare several techniques to drive the singlet–triplet coherence in strongly coupled spin pairs. First, we study different methods for efficient excitation of the outer singlet–triplet coherences. The achieved conversion efficiency of magnetization to the coherences of interest is close to the theoretically allowed maximum. Second, we propose methods to convert the outer coherences into the inner singlet–triplet coherence. The inner singlet–triplet coherence is insensitive to field inhomogeneity and can be long-lived. By probing this coherence, we perform a very precise measurement of the spin–spin J-couplings. A remarkable property of this coherence is that it can be preserved even in absence of a spin-locking radiofrequency field. Consequently, it is possible to shuttle the sample between different magnetic fields preserving the coherence. This allows one to study the field dependence of the relaxation time, TIST, of the inner singlet–triplet coherence by performing field-cycling experiments. We observed dramatic changes of the ratio TIST/T1 from about 1 (in strong fields) up to 2.4 (in weak fields), which is the evidence of a significant influence of the chemical shift anisotropy on relaxation. We have detected a remarkably long lifetime of the inner singlet–triplet coherence of about 200 s at the magnetic field of 5 mT.
1463-9076
6087-6100
Ivanov, Konstantin L.
8a0f5dff-c757-4abe-adbd-5bcd0385f440
Sheberstov, Kirill F.
0def36f7-c37b-4e18-924c-fe6a3c39515c
Kiryutin, Alexey S.
ddd6447c-ae2b-400c-a152-3d8d19ef5fba
Yurkovskaya, Alexandra V.
b8ca021e-676f-4fe0-8a2a-6173f59050c7
Levitt, Malcolm H.
bcc5a80a-e5c5-4e0e-9a9a-249d036747c3
Pileio, Giuseppe
13f78e66-0707-4438-b9c9-6dbd3eb7d4e8
Brown, Richard C.D.
21ce697a-7c3a-480e-919f-429a3d8550f5
Brown, Lynda J.
75aa95fa-5d27-46a7-9dbe-0f465a664f5b
Ivanov, Konstantin L.
8a0f5dff-c757-4abe-adbd-5bcd0385f440
Sheberstov, Kirill F.
0def36f7-c37b-4e18-924c-fe6a3c39515c
Kiryutin, Alexey S.
ddd6447c-ae2b-400c-a152-3d8d19ef5fba
Yurkovskaya, Alexandra V.
b8ca021e-676f-4fe0-8a2a-6173f59050c7
Levitt, Malcolm H.
bcc5a80a-e5c5-4e0e-9a9a-249d036747c3
Pileio, Giuseppe
13f78e66-0707-4438-b9c9-6dbd3eb7d4e8
Brown, Richard C.D.
21ce697a-7c3a-480e-919f-429a3d8550f5
Brown, Lynda J.
75aa95fa-5d27-46a7-9dbe-0f465a664f5b

Ivanov, Konstantin L., Sheberstov, Kirill F., Kiryutin, Alexey S., Yurkovskaya, Alexandra V., Levitt, Malcolm H., Pileio, Giuseppe, Brown, Richard C.D. and Brown, Lynda J. (2019) Excitation of singlet-triplet coherences in pairs of nearly-equivalent spins. Physical Chemistry Chemical Physics, 6087-6100. (doi:10.1039/C9CP00451C).

Record type: Article

Abstract

We present approaches for an efficient excitation of singlet–triplet coherences in pairs of nearly-equivalent spins. Standard Nuclear Magnetic Resonance (NMR) pulse sequences do not excite these coherences at all or with very low efficiency. The single quantum singlet–triplet coherences, here termed the outer singlet–triplet coherences, correspond to lines of low intensity in the NMR spectrum of a strongly-coupled spin pair (they are sometimes referred to as “forbidden transitions”), whereas the zero-quantum coherences, here termed the inner singlet–triplet coherences, do not have a direct spectral manifestation. In the present study, we investigated singlet–triplet coherences in a pair of nearly-equivalent carbon spins of the 13C-isotopomer of a specially designed naphthalene derivative with optimized relaxation properties. We propose and compare several techniques to drive the singlet–triplet coherence in strongly coupled spin pairs. First, we study different methods for efficient excitation of the outer singlet–triplet coherences. The achieved conversion efficiency of magnetization to the coherences of interest is close to the theoretically allowed maximum. Second, we propose methods to convert the outer coherences into the inner singlet–triplet coherence. The inner singlet–triplet coherence is insensitive to field inhomogeneity and can be long-lived. By probing this coherence, we perform a very precise measurement of the spin–spin J-couplings. A remarkable property of this coherence is that it can be preserved even in absence of a spin-locking radiofrequency field. Consequently, it is possible to shuttle the sample between different magnetic fields preserving the coherence. This allows one to study the field dependence of the relaxation time, TIST, of the inner singlet–triplet coherence by performing field-cycling experiments. We observed dramatic changes of the ratio TIST/T1 from about 1 (in strong fields) up to 2.4 (in weak fields), which is the evidence of a significant influence of the chemical shift anisotropy on relaxation. We have detected a remarkably long lifetime of the inner singlet–triplet coherence of about 200 s at the magnetic field of 5 mT.

Text
60. ST coherences - Accepted Manuscript
Restricted to Repository staff only until 18 February 2020.
Request a copy

More information

Accepted/In Press date: 18 February 2019
e-pub ahead of print date: 18 February 2019

Identifiers

Local EPrints ID: 428840
URI: https://eprints.soton.ac.uk/id/eprint/428840
ISSN: 1463-9076
PURE UUID: 855c0afe-2254-48ea-a297-7a312a055a88
ORCID for Malcolm H. Levitt: ORCID iD orcid.org/0000-0001-9878-1180
ORCID for Giuseppe Pileio: ORCID iD orcid.org/0000-0001-9223-3896
ORCID for Richard C.D. Brown: ORCID iD orcid.org/0000-0003-0156-7087
ORCID for Lynda J. Brown: ORCID iD orcid.org/0000-0002-5678-0814

Catalogue record

Date deposited: 11 Mar 2019 17:30
Last modified: 20 Jun 2019 00:37

Export record

Altmetrics

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×