1
|
Kitzmann WR, Freudenthal J, Reponen APM, VanOrman ZA, Feldmann S. Fundamentals, Advances, and Artifacts in Circularly Polarized Luminescence (CPL) Spectroscopy. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2302279. [PMID: 37658497 DOI: 10.1002/adma.202302279] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 05/06/2023] [Indexed: 09/03/2023]
Abstract
Objects are chiral when they cannot be superimposed with their mirror image. Materials can emit chiral light with an excess of right- or left-handed circular polarization. This circularly polarized luminescence (CPL) is key to promising future applications, such as highly efficient displays, holography, sensing, enantiospecific discrimination, synthesis of drugs, quantum computing, and cryptography. Here, a practical guide to CPL spectroscopy is provided. First, the fundamentals of the technique are laid out and a detailed account of recent experimental advances to achieve highly sensitive and accurate measurements is given, including all corrections required to obtain reliable results. Then the most common artifacts and pitfalls are discussed, especially for the study of thin films, for example, based on molecules, polymers, or halide perovskites, as opposed to dilute solutions of emitters. To facilitate the adoption by others, custom operating software is made publicly available, equipping the reader with the tools needed for successful and accurate CPL determination.
Collapse
Affiliation(s)
- Winald R Kitzmann
- Department of Chemistry, Johannes Gutenberg University, Duesbergweg 10-14, 55122, Mainz, Germany
- Rowland Institute, Harvard University, 100 Edwin H. Land Boulevard, Cambridge, MA, 02142, USA
| | - John Freudenthal
- Hinds Instruments Inc., 7245 NE Evergreen Parkway, Hillsboro, OR, 97124, USA
| | - Antti-Pekka M Reponen
- Rowland Institute, Harvard University, 100 Edwin H. Land Boulevard, Cambridge, MA, 02142, USA
| | - Zachary A VanOrman
- Rowland Institute, Harvard University, 100 Edwin H. Land Boulevard, Cambridge, MA, 02142, USA
| | - Sascha Feldmann
- Rowland Institute, Harvard University, 100 Edwin H. Land Boulevard, Cambridge, MA, 02142, USA
| |
Collapse
|
2
|
Forbes KA, Bradshaw DS, Andrews DL. Influence of chirality on fluorescence and resonance energy transfer. J Chem Phys 2019; 151:034305. [PMID: 31325950 DOI: 10.1063/1.5109844] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Electronically excited molecules frequently exhibit two distinctive decay mechanisms that rapidly generate optical emission: one is direct fluorescence and the other is energy transfer to a neighboring component. In the latter, the process leading to the ensuing "indirect" fluorescence is known as FRET, or fluorescence resonance energy transfer. For chiral molecules, both fluorescence and FRET exhibit discriminatory behavior with respect to optical and material handedness. While chiral effects such as circular dichroism are well known, as too is chiral discrimination for FRET in isolation, this article presents a study on a stepwise mechanism that involves both. Chirally sensitive processes follow excitation through the absorption of circularly polarized light and are manifest in either direct or indirect fluorescence. Following recent studies setting down the symmetry principles, this analysis provides a rigorous, quantum outlook that complements and expands on these works. Circumventing expressions that contain complicated tensorial components, our results are amenable for determining representative numerical values for the relative importance of the various coupling processes. We discover that circular dichroism exerts a major influence on both fluorescence and FRET, and resolving the engagement of chirality in each component reveals the distinct roles of absorption and emission by, and between, donor and acceptor pairs. It emerges that chiral discrimination in the FRET stage is not, as might have been expected, the main arbiter in the stepwise mechanism. In the concluding discussion on various concepts, attention is focused on the validity of helicity transfer in FRET.
Collapse
Affiliation(s)
- Kayn A Forbes
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - David S Bradshaw
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - David L Andrews
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| |
Collapse
|
3
|
Abstract
Optical polarization features associated with the fundamental processes of molecular fluorescence and resonance energy transfer are in general studied with reference to plane polarizations. When any of the species involved is chiral, the associated emission processes may exhibit an element of circular polarization-a degree of optical helicity. Although usually a minor effect, some systems can exhibit a sizeable component of circularly polarized luminescence, whose helicity correlates with the enantiomeric form. In studies of multi-component systems, in which initial excitation of a donor species-followed by energy transfer-leads to emission from an acceptor molecule, the handedness of both donor and acceptor may influence output circularity. In systems with an achiral acceptor, a degree of fluorescence circularity may be influenced by the handedness of a chiral donor, but this should not be construed in terms of 'conveying' chirality. Chiral molecules may also play a passive role by inducing helicity in the fluorescence from achiral neighbours, and further tiers of complexity arise if the initial excitation is itself of circular polarization. In all such processes, symmetry principles play a major role in determining a sensitivity to molecular handedness, and their detailed consideration enables a range of new experimental procedures to be identified. Casting the fundamental theory in terms of formal photon-molecule couplings enables the quantum mechanisms involved in all such phenomena to be clearly resolved. The results provide fresh physical insights, and establish connections across a range of indirectly related chiroptical phenomena including induced circular dichroism.
Collapse
Affiliation(s)
- David L Andrews
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| |
Collapse
|
4
|
Kumar J, Nakashima T, Kawai T. Circularly Polarized Luminescence in Chiral Molecules and Supramolecular Assemblies. J Phys Chem Lett 2015; 6:3445-52. [PMID: 26269090 DOI: 10.1021/acs.jpclett.5b01452] [Citation(s) in RCA: 431] [Impact Index Per Article: 47.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Circularly polarized luminescence, or CPL, is a luminescence phenomenon that provides the differential emission intensity of right and left circularly polarized light, thereby providing information on the excited state properties of the chiral molecular systems. In recent years, there has been a growing interest toward the development of organic chromophores capable of circularly polarized emission due to their potential applications in sensors, asymmetric synthesis as well as display and optical storage devices. The major drawback with organic molecules is the low dissymmetric factors exhibited by these systems. One of the recent strategies adopted for the improvement in luminescence dissymmetry of organic systems is through the controlled self-assembly of chromophores. In this Perspective, we highlight the recent experimental and theoretical developments in the field of chiral organic chromophoric systems and their self-assembly, that has produced promising results toward the enhancement of glum values in CPL.
Collapse
Affiliation(s)
- Jatish Kumar
- Graduate School of Materials Science, Nara Institute of Science and Technology, NAIST , 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
| | - Takuya Nakashima
- Graduate School of Materials Science, Nara Institute of Science and Technology, NAIST , 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
| | - Tsuyoshi Kawai
- Graduate School of Materials Science, Nara Institute of Science and Technology, NAIST , 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
| |
Collapse
|
5
|
Samuel APS, Lunkley JL, Muller G, Raymond KN. Strong Circularly Polarized Luminescence from Highly Emissive Terbium Complexes in Aqueous Solution. Eur J Inorg Chem 2010; 2010:3343-3347. [PMID: 20730030 PMCID: PMC2922774 DOI: 10.1002/ejic.201000309] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Indexed: 11/11/2022]
Abstract
Two luminescent terbium(III) complexes have been prepared from chiral ligands containing 2-hydroxyisophthalamide (IAM) antenna chromophores and their non-polarized and circularly-polarized luminescence properties have been studied. These tetradentate ligands, which form 2:1 ligand/Tb(III) complexes, utilize diaminocyclohexane (cyLI) and diphenylethylenediamine (dpenLI) backbones, which we reasoned would impart conformational rigidity and result in Tb(III) complexes that display both large luminescence quantum yield (Φ) values and strong circularly polarized luminescence (CPL) activities. Both Tb(III) complexes are highly emissive, with Φ values of 0.32 (dpenLI-Tb) and 0.60 (cyLI-Tb). Luminescence lifetime measurements in H(2)O and D(2)O indicate that while cyLI-Tb exists as a single species in solution, dpenLI-Tb exists as two species: a monohydrate complex with one H(2)O molecule directly bound to the Tb(III) ion and a complex with no water molecules in the inner coordination sphere. Both cyLI-Tb and dpenLI-Tb display increased CPL activity compared to previously reported Tb(III) complexes made with chiral IAM ligands. The CPL measurements also provide additional confirmation of the presence of a single emissive species in solution in the case of cyLI-Tb, and multiple emissive species in the case of dpenLI-Tb.
Collapse
Affiliation(s)
- Amanda P. S. Samuel
- Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA, Fax: +1-510-486-5283,
| | - Jamie L. Lunkley
- Department of Chemistry, San José State University, San José, CA 95192-0101
| | - Gilles Muller
- Department of Chemistry, San José State University, San José, CA 95192-0101
| | - Kenneth N. Raymond
- Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA, Fax: +1-510-486-5283,
| |
Collapse
|
6
|
Imai Y, Shiota N, Kinuta T, Okuno T, Nakano Y, Harada T, Sato T, Fujiki M, Kuroda R, Matsubara Y. A 2D Layered Chiral Supramolecular Organic Fluorophore Composed of 1-Amino-2-indanol and Carboxylic Acid Derivatives. European J Org Chem 2010. [DOI: 10.1002/ejoc.200901192] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
7
|
Circularly Polarized Luminescence (CPL) of Proteins and Protein Complexes. REVIEWS IN FLUORESCENCE 2008 2010. [DOI: 10.1007/978-1-4419-1260-2_18] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
|
8
|
Seitz M, Do K, Ingram AJ, Moore EG, Muller G, Raymond KN. Circularly polarized luminescence in enantiopure europium and terbium complexes with modular, all-oxygen donor ligands. Inorg Chem 2009; 48:8469-79. [PMID: 19639983 PMCID: PMC2735592 DOI: 10.1021/ic901079s] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The modular syntheses of three new octadentate, enantiopure ligands are reported, one with the bidentate chelating unit 2-hydroxyisophthalamide (IAM) and two with bidentate 1-hydroxy-2-pyridinone (1,2-HOPO) units. A new design principle is introduced for the chiral, non-racemic hexamines which constitute the central backbones for the presented class of ligands. The terbium(III) complex of the IAM ligand, as well as the europium(III) complexes of the 1,2-HOPO ligands, are synthesized and characterized by various techniques (NMR, UV, CD, luminescence spectroscopy). All species exhibit excellent stability and moderate to high luminescence efficiency (quantum yields Phi(Eu) = 0.05-0.08 and Phi(Tb) = 0.30-0.57) in aqueous solution at physiological pH. Special focus is put onto the properties of the complexes in regard to circularly polarized luminescence (CPL). The maximum luminescence dissymmetry factors (g(lum)) in aqueous solution are high with |g(lum)|(max) = 0.08-0.40. Together with the very favorable general properties (good stability, high quantum yields, long lifetimes), the presented lanthanide complexes can be considered as good candidates for analytical probes based on CPL in biologically relevant environments.
Collapse
Affiliation(s)
- Michael Seitz
- Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA
| | - King Do
- Department of Chemistry, San José State University, San José, CA 95192-0101, USA
| | - Andrew J. Ingram
- Department of Chemistry, San José State University, San José, CA 95192-0101, USA
| | - Evan G. Moore
- Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA
| | - Gilles Muller
- Department of Chemistry, San José State University, San José, CA 95192-0101, USA
| | - Kenneth N. Raymond
- Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA
| |
Collapse
|
9
|
Crassous J. Chiral transfer in coordination complexes: towards molecular materials. Chem Soc Rev 2009; 38:830-45. [DOI: 10.1039/b806203j] [Citation(s) in RCA: 347] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
10
|
Seitz M, Moore EG, Ingram AJ, Muller G, Raymond KN. Enantiopure, octadentate ligands as sensitizers for europium and terbium circularly polarized luminescence in aqueous solution. J Am Chem Soc 2007; 129:15468-70. [PMID: 18031042 PMCID: PMC2636552 DOI: 10.1021/ja076005e] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Michael Seitz
- Department of Chemistry, University of California, Berkeley, California 94720-1460, USA
| | | | | | | | | |
Collapse
|
11
|
Kawai T, Kawamura K, Tsumatori H, Ishikawa M, Naito M, Fujiki M, Nakashima T. Circularly Polarized Luminescence of a Fluorescent Chiral Binaphtylene–Perylenebiscarboxydiimide Dimer. Chemphyschem 2007; 8:1465-8. [PMID: 17557371 DOI: 10.1002/cphc.200600747] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Tsuyoshi Kawai
- Graduate School of Materials Science, Nara Institute of Science and Technology, NAIST, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan.
| | | | | | | | | | | | | |
Collapse
|
12
|
Gawryszewska P, Legendziewicz J, Ciunik Z, Esfandiari N, Muller G, Piguet C, Cantuel M, Riehl JP. On the determination of empirical absolute chiral structure: Chiroptical spectrum correlations for D3 lanthanide (III) complexes. Chirality 2006; 18:406-12. [PMID: 16575878 DOI: 10.1002/chir.20270] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Circularly polarized luminescence (CPL) from selected transitions of Eu(III) in resolved single crystals of Na3[Eu(ODA)3].2NaClO4.6H2O are compared to CPL results obtained from solutions containing perturbed racemic mixtures of Eu(2,6-pyridine-dicarboxylate)3 (3-) and enantiomerically pure d-f helicate LambdaLambda-(-)EuCr(L8)3] in order to determine an empirical relationship between helicity and CPL spectra. Comparison of the CPL results, even for the magnetic dipole allowed transitions of Eu(III) where one measures large chiral discrimination, shows that the signs and magnitudes do not correlate with the overall helicity of the Eu(III) site. It is concluded that the symmetry of the Eu(III) site in LambdaLambda-(-)EuCr(L8)3 is not close enough to D3 to allow for the confirmation of the presumed spectra:structure correlation.
Collapse
Affiliation(s)
- P Gawryszewska
- Faculty of Chemistry, University of Wrocław, Wrocław, Poland
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Gawryszewska P, Sokolnicki J, Dossing A, Riehl JP, Muller G, Legendziewicz J. Characterization of the Electronic Excited-State Energetics and Solution Structure of Lanthanide(III) Complexes with the Polypyridine Ligand 6,6‘-Bis[bis(2-pyridylmethyl)aminomethyl]-2,2‘-bipyridine. J Phys Chem A 2005; 109:3858-63. [PMID: 16833702 DOI: 10.1021/jp0444666] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Absorption, emission, and excitation spectra for solid-state and solution of Tb(III), Dy(III), and Gd(III) complexes with the polypyridine ligand 6,6'-bis[bis(2-pyridylmethyl)-aminomethyl]-2,2'-bipyridine (C36H34N8) are presented. Measurements of excited-state lifetimes and quantum yields in various solvents at room temperature and 77 K are also reported and used to characterize the excited-state energetics of this system. Special attention is given to the characterization of metal-to-ligand energy transfer efficiency and mechanisms. The measurement of circularly polarized luminescence (CPL) from the solution of the Dy(III) complex following circularly polarized excitation confirms the chiral structure of the complexes under study. No CPL is present in the luminescence from the Eu(III) or Tb(III) complex because of efficient racemization. The variation of the magnitude of the CPL as a function of temperature from an aqueous solution of DyL is used for the first time to characterize the solution equilibria between different chiral species.
Collapse
Affiliation(s)
- P Gawryszewska
- Faculty of Chemistry, University of Wrocław, 14 F. Joliot-Curie Street, 50-383 Wrocław, Poland
| | | | | | | | | | | |
Collapse
|
14
|
Atkinson P, Bretonnière Y, Parker D, Muller G. NMR and Luminescence Binding Studies of Ytterbium, Thulium, and Europium Macrocyclic Complexes with Phosphorus(V) Oxy Anions. Helv Chim Acta 2005. [DOI: 10.1002/hlca.200590025] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
15
|
Riehl JP, Muller G. Circularly Polarized Luminescence Spectroscopy from Lanthanide Systems. HANDBOOK ON THE PHYSICS AND CHEMISTRY OF RARE EARTHS 2004. [DOI: 10.1016/s0168-1273(04)34003-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
|
16
|
Thompson NC, Parker D, Schmitt-Willich H, Sulzle D, Muller G, Riehl JP. NMR and chiroptical examination of the diastereoisomers of (S)-Eu–EOB–DTPA. Dalton Trans 2004:1892-5. [PMID: 15381997 DOI: 10.1039/b403863k] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The solution structure of the diastereoisomers of (S)-Eu--EOB--DTPA has been analysed by (1)H NMR, CD and CPL spectroscopy. Two major species exist which possess very similar (1)H NMR paramagnetic shifts and emission spectra, consistent with a 9-coordinate structure involving one bound water. Circularly polarised luminescence data are consistent with a common Lambda-helicity for each isomer; the isomers differ only in the absolute configuration of the central nitrogen atom.
Collapse
Affiliation(s)
- Nicola C Thompson
- Department of Chemistry, University of Durham, South Road, Durham, UK DH1 3LE
| | | | | | | | | | | |
Collapse
|
17
|
Parker D, Dickins RS, Puschmann H, Crossland C, Howard JAK. Being excited by lanthanide coordination complexes: aqua species, chirality, excited-state chemistry, and exchange dynamics. Chem Rev 2002; 102:1977-2010. [PMID: 12059260 DOI: 10.1021/cr010452+] [Citation(s) in RCA: 675] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- David Parker
- Department of Chemistry, University of Durham, South Road, Durham, DH1 3LE, U.K.
| | | | | | | | | |
Collapse
|
18
|
Maupin CL, Dickins RS, Govenlock LG, Mathieu CE, Parker D, Williams JAG, Riehl JP. The Measurement of Circular Polarization in the Near-IR Luminescence from Chiral Complexes of Yb(III) and Nd(III). J Phys Chem A 2000. [DOI: 10.1021/jp000648y] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Christine L. Maupin
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, and Department of Chemistry, University of Durham, South Road Durham, U.K. DH1 3LE
| | - Rachel S. Dickins
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, and Department of Chemistry, University of Durham, South Road Durham, U.K. DH1 3LE
| | - Linda G. Govenlock
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, and Department of Chemistry, University of Durham, South Road Durham, U.K. DH1 3LE
| | - Celine E. Mathieu
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, and Department of Chemistry, University of Durham, South Road Durham, U.K. DH1 3LE
| | - David Parker
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, and Department of Chemistry, University of Durham, South Road Durham, U.K. DH1 3LE
| | - J. A. Gareth Williams
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, and Department of Chemistry, University of Durham, South Road Durham, U.K. DH1 3LE
| | - James P. Riehl
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, and Department of Chemistry, University of Durham, South Road Durham, U.K. DH1 3LE
| |
Collapse
|
19
|
Brittain HG. Applications of chiroptical spectroscopy for the characterization of pharmaceutical compounds. J Pharm Biomed Anal 1998; 17:933-40. [PMID: 9884185 DOI: 10.1016/s0731-7085(98)00061-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Many pharmaceutical compounds contain one or more centers of dissymmetry, thus presenting a unique series of regulatory and compendial requirements. Although most often characterized using chiral chromatography, these molecules can be effectively studied using the various techniques of chiroptical spectroscopy. Techniques which have been found to be very useful for such work include polarimetry, optical rotatory dispersion, circular dichroism, and circularly polarized luminescence. The principles underlying each effect will be briefly outlined, and the application of each illustrated through the inclusion of appropriate examples.
Collapse
Affiliation(s)
- H G Brittain
- Acute Therapeutics, Inc., Maplewood, NJ 07040, USA.
| |
Collapse
|
20
|
Abstract
The addition of circular or, more generally, elliptical polarization state detection to fast optical absorption spectroscopy can increase the amount of electronic and nuclear conformational information obtained about transient molecular species. To accomplish this, fast circular dichroism methods have emerged over the past decade that overcome the millisecond limit on time resolution associated with conventional modulation techniques and enable structural studies of excited states and kinetic intermediates. This article reviews techniques for time-resolved natural and magnetic circular dichroism spectroscopy covering the picosecond to millisecond time regimes and their applications, with particular emphasis on quasi-null ellipsometric techniques for nanosecond multichannel measurements of circular dichroism. Closely related quasi-null polarimetric techniques for nanosecond optical rotatory dispersion and linear dichroism measurements are also discussed.
Collapse
Affiliation(s)
- R A Goldbeck
- Department of Chemistry and Biochemistry, University of California, Santa Cruz 95064-1077, USA.
| | | | | |
Collapse
|
21
|
|
22
|
|