We developed a robust nanosecond photonic crystal switching material by using poly(N-isopropylacrylamide) (PNIPAM) nanogel colloidal particles that self-assemble into crystalline arrays (CCAs). The CCA was polymerized loose-knit hydrogel which permits the individual embedded PNIPAM to coherently and synchronously undergo their thermally induced volume phase transitions. A laser T-jump from 30 35 degrees C actuates particle shrinkage; resulting increased diffraction decreases light...

We used UV resonance Raman (UVRR) spectroscopy to quantitatively correlate the peptide bond AmIII3 frequency its Psi Ramachandran angle and number types of amide hydrogen bonds at different temperatures. This information allows us develop a family relationships directly estimate from measured UVRR frequencies for (PBs) with known bonding (HB). These ignore more modest Phi dependence allow determination standard error +/-8 degrees , if HB state PB is known. normally case secondary structure...

Trp-cage, a synthetic 20 residue polypeptide, is proposed to be an ultrafast folding miniprotein which utilizes tertiary contacts define its native conformation. We utilized UV resonance Raman spectroscopy (UVRS) with 204 and 229 nm excitation follow thermal melting. Our results indicate that Trp-cage melting complex, it not simple two-state process. Using we probe the peptide secondary structure find Trp-cage's α-helix shows broad curve where on average four α-helical amide bonds melt upon...

We examined the 204-nm UV Raman spectra of peptide XAO, which was previously found by Shi et al.'s NMR study to occur in aqueous solution a polyproline II (PPII) conformation (Proc. Natl. Acad. Sci. U.S.A. 2002, 99, 9190). The XAO are essentially identical small peptides such as ala5 and large 21-residue predominantly Ala peptide, AP. conclude that non-α-helical conformations these dominantly PPII. Thus, AP, is highly α-helical at room temperature, melts PPII conformation. There no...

We measured the 229 nm absolute ultraviolet (UV) Raman cross-sections of explosives trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), cyclotrimethylene-trinitramine (RDX), chemically related nitroamine explosive HMX, and ammonium nitrate in solution. The are 1000-fold greater than those excited near-infrared visible spectral regions. Deep UV resonance spectroscopy enables detection at parts-per-billion (ppb) concentrations may prove useful for stand-off spectroscopic explosives.

UV resonance Raman (UVR) spectroscopy was used to examine the solution conformation of poly-l-lysine (PLL) and poly-l-glutamic acid (PGA) in their non-α-helical states. UVR measurements indicate that PLL (at pH = 2) PGA 9) exist mainly a mixture polyproline II (PPII) novel left-handed 2.51-helical conformation, which is an extended β-strand-like with Ψ ≈ +170° Φ −130°. Both these conformations are highly exposed water. The energies very similar. We see no evidence any disordered "random...

We investigated the assignments and conformational dependencies of UV resonance Raman bands 21-residue mainly alanine peptide (AP) its isotopically substituted derivatives in both their α-helical PPII states. also examined smaller peptides to correlate conformation, hydrogen bonding, structure. Our vibrational mode analysis confirms complex nature amide III region, which contains many modes. assign these by interpreting induced frequency shifts sensitivity temperature dependence. some cases...

We describe a state-of-the-art tunable ultraviolet (UV) Raman spectrometer for the 193-270 nm spectral region. This instrument allows steady-state and transient UV measurements. utilize 5 kHz Ti-sapphire continuously laser (approximately 20 ns pulse width) between 193 240 For measurements we one Coherent Infinity YAG to generate nanosecond infrared (IR) pump pulses temperature jump (T-jump) second that is frequency tripled shifted into deep (204 nm) excitation. Numerous other excitation...

Abstract We have developed photochemically controlled photonic crystals that may be useful in novel recordable and erasable memories and/or display devices. These materials can operate the UV, visible, or near‐IR spectral regions. Information is recorded erased by exciting crystal with ∼ 360 nm UV light 480 visible light. The information read out measuring diffraction wavelength. active element of device an azobenzene‐functionalized hydrogel, which contains embedded crystalline colloidal...

We examined the 204-nm UV resonance Raman (UVR) spectra of polyproline II (PPII) and α-helical states a 21-residue mainly alanine peptide (AP) in different H2O/D2O mixtures. Our hypothesis is that if amide backbone vibrations are coupled, then partial deuteration N will perturb frequencies cross sections since coupling be interrupted; partially deuterated derivatives not simply sum fully protonated peptides. find UVR AmIII AmII' bands both PPII conformation (and also AmI, AmI', AmII bands)...

Abstract A molecular rotational resonance spectroscopy method for measuring the enantiomeric excess of pantolactone, an intermediate in synthesis panthenol and pantothenic acid, is presented. The enantiomers are distinguished via complexation with a small chiral tag molecule, which produces diastereomeric complexes pulsed jet expansion used to inject sample into spectrometer. These have distinct moments inertia, so their spectra resolved by MRR spectroscopy. Quantitative (EE) measurements...

Online monitoring of chemical reactions by using analytical chemistry tools is a powerful way to maximize control over these processes. In this paper, we demonstrate the use molecular rotational resonance, an emerging and extraordinarily selective spectroscopic technique, perform automated reaction measurements. An interface six-port valve with calibrated sample loop, coupled temperature controlled inlet for analyte volatilization, was developed tested. Two were chosen initial...

We used UV resonance Raman (UVRR) spectroscopy exciting at approximately 200 nm within the peptide bond pi --> pi* transitions to selectively study amide vibrations of bonds during alpha-helix melting. The dependence frequencies on their Psi Ramachandran angles and hydrogen bonding enables us, for first time, experimentally determine temperature angle population distribution a 21-residue mainly alanine peptide. These distributions allow us easily discriminate between alpha-helix, 3(10)-helix...

UV resonance Raman spectroscopy has been used to determine the conformational energy landscape of poly-l-lysine (PLL) in presence NaClO4 as a function temperature. At 1 °C, 0.83 M NaClO4, PLL shows an ∼86% α-helix-like content, which contains α-helix and π-bulge/helix conformations. The high content occurs because charge screening due strong ion-pair formation between ClO4- lysine side chain −NH3+. As temperature increases from 60 conformations melt into extended (PPII 2.51-helix). We...

We used ultraviolet resonance Raman (UVRR) spectra to examine the spatial dependence and thermodynamics of α-helix melting an isotopically labeled α-helical, 21-residue, mainly alanine peptide. The peptide was synthesized with six natural abundance amino acids at center perdeuterated residues elsewhere. Cα deuteration a bond decouples Cα−H bending from N−H bending, which significantly shifts random coil conformation amide III band; this shift clearly resolves it band nondeuterated bonds....

We used UV resonance Raman (UVRR) to examine the spatial dependence of T-jump secondary structure relaxation an isotopically labeled 21-residue mainly Ala peptide, AdP. The AdP penultimate residues were perdeuterated, leaving central hydrogenated, allow separate monitoring melting middle versus end peptide bonds. For 5 30 degrees C T-jumps, bonds show a approximately 2-fold slower time (189 +/- 31 ns) than do exterior (97 15 ns). In contrast, for 20 40 T-jump, bond appears be faster (56 6...

UV resonance Raman spectra (UVRS) of an α-helical, 21 residue, mainly Ala peptide (AP) in the dehydrated solid state were compared to those aqueous solution at different temperatures. The UVRS amide band frequencies a α-helix show frequency shifts due loss backbone hydrogen bonding water; II and III bands downshift, while I upshifts. are identical direction but smaller than that occur for α-helices as temperature increases; water strengths decrease increases. can be used monitor bonding.

We designed and demonstrated the unique abilities of first gas chromatography-molecular rotational resonance spectrometer (GC-MRR). While broadly routinely applicable, its capabilities can exceed those high-resolution MS NMR spectroscopy in terms selectivity, resolution, compound identification. A series 24 isotopologues isotopomers five organic compounds are separated, identified, quantified a single run. Natural isotopic abundances mixtures containing chlorine, bromine, sulfur heteroatoms...

Abstract We designed and demonstrated the unique abilities of first gas chromatography–molecular rotational resonance spectrometer (GC‐MRR). While broadly routinely applicable, its capabilities can exceed those high‐resolution MS NMR spectroscopy in terms selectivity, resolution, compound identification. A series 24 isotopologues isotopomers five organic compounds are separated, identified, quantified a single run. Natural isotopic abundances mixtures containing chlorine, bromine, sulfur...

We demonstrate a calculated α-helix peptide folding energy landscape which accurately simulates the first experimentally measured melting landscape. examine 21-amino acid, mainly polyalanine and calculate free along Ψ Ramachandran angle secondary coordinate. The experimental was determined using UV resonance Raman spectroscopy. relative values are very close as equilibrium conformations. find 2.3 kcal/mol activation barriers between α-helix-like PPII-like basins. also that conformations...

A next-generation gas chromatograph-molecular rotational resonance (MRR) spectrometer (GC-MRR) with instrumental improvements and higher sensitivity is described. MRR serves as a structural information-rich detector for GC extremely narrow linewidths capabilities surpassing 1H nuclear magnetic resonance/Fourier transform infrared spectroscopy/mass spectrometry (MS) while offering unparalleled specificity in regard to molecule's three-dimensional structure. With Fabry–Pérot cavity supersonic...

We built a transient absorption spectrophotometer that can determine spectral changes occur at times as fast ∼200 ns and slow minute. The be induced by temperature-jump (T-jump) or optical pumping from the deep ultraviolet (UV) to infrared (IR) use of single Nd:YAG laser pulses. Our fiber-optic spectrometer coupled XeF flashlamp makes collection spectra easy convenient in range near IR (1700 nm) down UV (200 nm), with high signal-to-noise (S/N) ratios. resolution is determined specific...

This paper reports our efforts to determine whether rotational spectroscopy is a useful tool for petroleum analysis. These include the use of BrightSpec molecular resonance (MRR) spectrometer, which operates in 260-290 GHz frequency range, record spectra small polar contaminants commercial gasoline. The observed showed rich, but assignable, patterns due sensitivity MRR only compounds. Any interference from complex hydrocarbon matrix, conventional chromatographic methods obscures signals...

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