Solvent/Solute Interactions Probed by Picosecond Transient-Raman Spectroscopy

Gustafson, Terry L.; Morris, D. L.; Huston, Lisa A.; Butler, R.M.; Noda, Isao

doi:10.1007/978-3-642-85060-8_32

“…Indigo, however, is poorly soluble in water, which could introduce some artifacts because of the aggregates. Moreover, it is well-known that the solvent plays an important role in the relaxation path to the ground state. , Nagasawa et al studied the transient absorption of indigo carmine with different solvents, and they showed a similar lifetime in DMSO solvent (92 ps) when compared with our results and a much shorter lifetime for water solution (2.7 ps), the opposite from the Kobayashi results. The time resolution in Kobayashi experiments is, however, much worse (8.5 ps) when compared with Nagasawa and ours (0.15 ps).…”

Section: Resultscontrasting

confidence: 69%

Time-Resolved Spectroscopy of Indigo and of a Maya Blue Simulant

Bernardino

¹

,

Brown-Xu

²

,

Gustafson

³

et al. 2016

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Maya Blue is a puzzling pigment found in objects produced by the ancient Maya civilization. It is a combination of indigo and palygorskite, and it is well-known for the high chemical and photochemical stability of the dye promoted by the clay confined environment. This pigment has survived over 1500 years, and it was first thought to be purely inorganic. The reasons for such stability have been investigated over the past years, and it may involve hydrogen bonds, complexation, and oxidation to dehydroindigo. However, these theories are not completely understood, and more evidence about indigo/palygorskite interactions must be obtained. In this study indigo and a Maya Blue simulant pigment were, for the first time, studied by transient absorption (TA) and time-resolved infrared (TRIR) spectroscopy. From such analysis it was possible to investigate the electronic excited states of indigo and the photochemistry behavior of the dye when interacting with the palygorskite. Concerning the TRIR measurements, the shifts of the C O and N−H vibrations indicate that hydrogen bonds are formed involving the dye and the coordinated water molecules present in the clay. Furthermore, a red shift is observed in the absorption of electronic ground state (50 nm) and also in the electronic excited state (27 nm) of Maya Blue simulant, suggesting that the excited states are stabilized by the clay. Indigo in DMSO solution presents a lifetime of ca. 120 ps while in the clay it becomes much shorter, ca. 3 ps. The shorter lifetime and also the red shift observed in the TA results suggest a stabilization of the first electronic excited state, which promotes a more efficient energy relaxation through conical intersection and, as a consequence, a faster excited state decay. Such factors can be important for the Maya Blue photostability, as they are also believed to be responsible for the high photostability of DNA and melanin.

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“…By taking advantage of the distinct transient waveform signature of Raman intensity signals, the 2D Raman study successfully separated the spectral contributions arising from radical anions and those from solvent background . Gustafson et al later applied the 2D correlation analysis to the picosecond transient Raman study of solvent/solute interactions for trans -4,4‘-diphenylstilbene in methylene chloride to accentuate the subtle effect observed in the course of a pump−probe experiment .…”

Section: Introductionmentioning

confidence: 99%

Two-Dimensional Raman (2D Raman) Correlation Spectroscopy Study of Non-oxidative Photodegradation of β-Carotene

Noda

¹

,

Marcott

²

2002

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Photoinduced decomposition reaction of all-trans-β-carotene in the absence of oxygen was studied by 2D Raman correlation spectroscopy. Generalized two-dimensional correlation analysis, coupled with NIR-excited Raman scattering measurements, reveals the presence of both simultaneous and sequential changes of Raman intensities associated with the decomposing β-carotene and the creation of photoreaction products. The largest intensity increase occurs for the Raman band at 1537 cm-1, which is likely due to the formation of a photoisomerization product containing one or more cis CC groups. The formation of this product occurs at an earlier stage of the reaction than the steady decrease of band intensities associated with all-trans-β-carotene at 1522 and 1520 cm-1. Smaller intensity increases at 1133, 1569, and 1284 cm-1 occur synchronously with the growth of the 1537 cm-1 band and prior to the overall decrease in the all-trans-β-carotene bands. Thus, the decomposition product associated with the Raman bands at 1133, 1569, and 1284 cm-1 are either due to the same decomposition product as that represented by the 1537 cm-1 band, or different products formed at the same rate. The intensities of Raman bands at 1005 and 1000 cm-1 decrease in intensity, but this decrease lags behind that observed in the main 1520 and 1520 cm-1 all-trans-β-carotene bands. These bands may represent spectral contributions from different decomposition products overlapped with the dominant β-carotene contribution as well as a toluene solvent band.

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“…Following this, Gustafson et al 62 used 2D correlation analysis for investigating picosecond transient Raman data for solvent-solute interactions. More recently, static 2D Raman correlation spectroscopy applications have also become very popular.…”

Section: Raman Spectroscopymentioning

confidence: 99%

“…Raman spectroscopy may now be used with similar success alongside mid-IR and NIR spectroscopy with 2D correlation spectroscopy. 61 -65,68 -71 In an analogous manner as with mid-IR and NIR spectroscopy, 2D Raman correlation spectroscopy has been utilized in the research of transient phenomena, 61,62 molecules, 63 polymers, 64,65,68,69,71 and proteins. 70 Hetero-spectral correlation analysis including Raman spectroscopy has also seen keen interest.…”

Section: Polymersmentioning

confidence: 99%

2 D Correlation Spectroscopy in Vibrational Spectroscopy

Ozaki¹

2001

Handbook of Vibrational Spectroscopy

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The sections in this article are Introduction IR Spectroscopy NIR Spectroscopy R aman Spectroscopy 2 D Hetero‐Spectral Correlation External Perturbation Applications of 2 D Mid‐ IR Spectroscopy Polymers Semicrystalline Polymers Immiscible Polymer Blends Dynamic IR Linear Dichroism and 2 D Correlation Spectroscopy of Poly(ɛ‐Caprolactone) Liquid Crystals Chemical Reactions Proteins Applications of 2 D NIR Spectroscopy Polymers Temperature‐Dependent Structural Variations of an Amorphous Polyamide Studied by 2 D NIR Spectroscopy Applications of 2 D Correlation Spectroscopy in Depth‐Profiling Photoacoustic Spectroscopy and NIR Dynamic Rheo‐Optics – Study of a Polymeric Laminate Film A 2 D NIR Correlation Spectroscopy Study on Composition‐Dependent Spectral Variations in Ethylene/Vinyl Acetate Copolymers Proteins Applications of 2 D R aman Spectroscopy Polymers Proteins Hetero‐Spectral Correlation Analysis 2 D R aman‐ NIR Hetero‐Spectral Correlation Analysis of the Specific Interactions in Partially Miscible Blends of Poly(Methyl Methacrylate) and Poly(4‐Vinylphenol) Conformational Changes of Ribonuclease a Upon Thermal Unfolding Studied by 2 D Mid‐ IR , NIR and IR ‐ NIR Hetero‐Spectral Correlation Spectroscopy

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Solvent/Solute Interactions Probed by Picosecond Transient-Raman Spectroscopy

Cited by 13 publications

References 16 publications

Time-Resolved Spectroscopy of Indigo and of a Maya Blue Simulant

Time-Resolved Spectroscopy of Indigo and of a Maya Blue Simulant

Two-Dimensional Raman (2D Raman) Correlation Spectroscopy Study of Non-oxidative Photodegradation of β-Carotene

2 D Correlation Spectroscopy in Vibrational Spectroscopy

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