Method for Evaluating Vibrational Mode Assignments in Surface-Bound Cyclic Hydrocarbons Using Sum-Frequency Generation

Buchbinder, Avram M.; Gibbs, Julianne M.; Stokes, Grace Y.; Peterson, Mark D.; Weitz, Eric; Geiger, Franz M.

doi:10.1021/jp205912h

Cited by 18 publications

(25 citation statements)

References 114 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Indeed, α-pinene and SOM prepared from it produce some of the strongest SFG signal intensities we have recorded in our laboratory from strongly ordered molecular systems, yielding signal responses as strong as those obtained from well-ordered self-assembled alkyl silanes on fused silica. 27,29,47 Whatever the detailed molecular origin of the strong SFG responses obtained from the particle material discussed here in Figure 4, we observe that the ssp-polarized SFG spectra of SOM prepared at the HEC and in the flow tube appear similar, irrespective of the pinene mix or the way the particles were prepared. For our setup, the SFG signal originates mainly from the particle/air interface and not from internal interfaces.…”

Section: Resultsmentioning

confidence: 69%

Vibrational Sum Frequency Generation Spectroscopy of Secondary Organic Material Produced by Condensational Growth from α-Pinene Ozonolysis

et al. 2013

Self Cite

View full text Add to dashboard Cite

Secondary organic material (SOM) was produced in a flow tube from α-pinene ozonolysis, and collected particles were analyzed spectroscopically via a nonlinear coherent vibrational spectroscopic technique, namely sum frequency generation (SFG). The SOM precursor α-pinene was injected into the flow tube reactor at concentrations ranging from 0.125 ± 0.01 ppm to 100 ± 3 ppm. The oxidant ozone was varied from 0.15 ± 0.02 to 194 ± 2 ppm. The residence time was 38 ± 1 s. The integrated particle number concentrations, studied using a scanning mobility particle sizer (SMPS), varied from no particles produced up to (1.26 ± 0.02) × 10(7) cm(-3) for the matrix of reaction conditions. The mode diameters of the aerosols increased from 7.7 nm (geometric standard deviation (gsd), 1.0) all the way to 333.8 nm (gsd, 1.9). The corresponding volume concentrations were as high as (3.0 ± 0.1) × 10(14) nm(3) cm(-3). The size distributions indicated access to different particle growth stages, namely condensation, coagulation, or combination of both, depending on reaction conditions. For filter collection and subsequent spectral analysis, reaction conditions were selected that gave a mode diameter of 63 ± 3 nm and 93 ± 3 nm, respectively, and an associated mass concentration of 12 ± 2 μg m(-3) and (1.2 ± 0.1) × 10(3) μg m(-3) for an assumed density of 1200 kg m(-3). Teflon filters loaded with 24 ng to 20 μg of SOM were analyzed by SFG. The SFG spectra obtained from particles formed under condensational and coagulative growth conditions were found to be quite similar, indicating that the distribution of SFG-active C-H oscillators is similar for particles prepared under both conditions. The spectral features of these flow-tube particles agreed with those prepared in an earlier study that employed the Harvard Environmental Chamber. The SFG intensity was found to increase linearly with the number of particles, consistent with what is expected from SFG signal production from particles, while it decreased at higher mass loadings of 10 and 20 μg, consistent with the notion that SFG probes the top surface of the SOM material following the complete coverage of the filter. The linear increase in SFG intensity with particle density also supports the notion that the average number of SFG active oscillators per particle is constant for a given particle size, that the particles are present on the collection filters in a random array, and that the particles are not coalesced. The limit of detection of SFG intensity was established as 24 ng of mass on the filter, corresponding to a calculated density of about 100 particles in the laser spot. As established herein, the technique is applicable for detecting low particle number or mass concentrations in ambient air. The related implication is that SFG is useful for short collection times and would therefore provide increased temporal resolution in a locally evolving atmospheric environment.

show abstract

Section: Resultsmentioning

confidence: 69%

Vibrational Sum Frequency Generation Spectroscopy of Secondary Organic Material Produced by Condensational Growth from α-Pinene Ozonolysis

et al. 2013

Self Cite

View full text Add to dashboard Cite

show abstract

“…In SFG spectroscopy, this frequency region is typically associated with aromatic C-H groups (Hommel and Allen, 2003;Kawaguchi et al, 2012), or vinylic groups (Buchbinder et al, 2009;Stokes et al, 2008Stokes et al, , 2009a, which are not present in these two species. While the SFG responses observed from epoxides 3 and 4 between 3050 and 3020 cm −1 are weak, they are likely to indicate the presence of the single methylene group attached to the strained epoxide ring structure in these compounds: previous SFG studies have shown that as the number of carbon atoms in a cyclic hydrocarbon decreases, and the C-C single bonds become increasingly strained, the vibrational frequencies of the methylene symmetric stretches shift beyond 3000 cm −1 (Buchbinder et al, 2011). Furthermore, the IR spectra of bromocyclopropane (Diallo and Waters, 1988), cyclopropane-d 1 (Diallo and Waters, 1988), cyclopropane-1,1-d 2 (Keeports and Eggers, 1984), cyclopropane 1,1,2,2-d 4 (Keeports and Eggers, 1984), and cyclopropane (Diallo and Waters, 1988;Spiekermann et al, 1980) all show vibrational responses beyond 3000 cm −1 .…”

Section: Epoxidesmentioning

confidence: 93%

“…However, the orientation of the oscillators that produce SFG signals may change based on what phase state they are in (Wei et al, 2001). By utilizing the ssp and ppp polarization combinations via the polarization intensity ratio method (Buchbinder et al, 2011;Moad and Simpson, 2004;Wang et al, 2005), the tilt angle of the C 3v symmetry axis and the associated distribution width of the methyl group of trans-β-IEPOX (epoxide 1) with respect to the surface normal were predicted. This molecule was chosen because the spectra of this molecule provide the best match to isoprene-derived SOA under both vapor and spin-coated conditions.…”

Section: Spectral Fitting and Molecular Orientation Analysismentioning

confidence: 99%

Towards the identification of molecular constituents associated with the surfaces of isoprene-derived secondary organic aerosol (SOA) particles

et al. 2014

View full text Add to dashboard Cite

Abstract. Secondary organic aerosol (SOA) particle formation ranks among the least understood chemical processes in the atmosphere, rooted in part in the lack of knowledge about chemical composition and structure at the particle surface, and little availability of reference compounds needed for benchmarking and chemical identification in pure and homogenous form. Here, we synthesize and characterize SOA particle constituents consisting of the isoprene oxidation products α-, δ-, and cis- and trans-β-IEPOX (isoprene epoxide), as well as syn- and anti-2-methyltetraol. Paying particular attention to their phase state (condensed vs. vapor), we carry out a surface-specific and orientationally selective chemical analysis by vibrational sum frequency generation (SFG) spectroscopy of these compounds in contact with a fused silica window. Comparison to the vibrational SFG spectra of synthetic isoprene-derived SOA particle material prepared at the Harvard Environmental Chamber yields a plausible match with trans-β-IEPOX, suggesting it is an abundant species on their surfaces, while the other species studied here, if present, appear to be SFG inactive and thus likely to be localized in a centrosymmetric environment, e.g., the particle bulk. No match is found for authentic SOA particle material collected at the site of the Amazonian Aerosol Characterization Experiment (AMAZE-08) with the surface SFG spectra of the compounds surveyed here, yet we cannot rule out this mismatch being attributable to differences in molecular orientation. The implications of our findings for SOA formation are discussed in the context of condensational particle growth and reactivity.

show abstract

“…10,16−18 Moreover, a set of polarization selection rules allows one to determine the symmetry of the vibrational transitions that give rise to particular spectral features. [13][14][15]19,20 Finally, the subwavenumber high-resolution broad-band SFG (HR-BB-SFG) spectrometer, recently developed at Pacific Northwest National Laboratory (PNNL), provides more than 1 order of magnitude improvement in spectral resolution when compared to conventional SFG spectrometers and has been shown to deliver nearly intrinsic SFG spectral line shapes for an accurate analysis of congested spectra. 15,18 These developments provide new opportunities for determining molecular structure by using surface and interfacial measurements as a means of expanding our molecular vibrational spectroscopy portfolio.…”

Section: Introductionmentioning

confidence: 99%

Accurate Line Shapes from Sub-1 cm^–1 Resolution Sum Frequency Generation Vibrational Spectroscopy of α-Pinene at Room Temperature

Mifflin

Velarde

et al. 2015

J. Phys. Chem. A

Self Cite

View full text Add to dashboard Cite

Despite the importance of terpenes in biology, the environment, and catalysis, their vibrational spectra remain unassigned. Here, we present subwavenumber high-resolution broad-band sum frequency generation (HR-BB-SFG) spectra of the common terpene (+)-α-pinene that reveal 10 peaks in the C-H stretching region at room temperature. The high spectral resolution resulted in spectra with more and better resolved spectral features than those of the Fourier transform infrared, femtosecond stimulated Raman spectra in the bulk condensed phase and those of the conventional BB-SFG and scanning SFG spectroscopy of the same molecule on a surface. Experiment and simulation show the spectral line shapes with HR-BB-SFG to be accurate. Homogeneous vibrational decoherence lifetimes of up to 1.7 ps are assigned to specific oscillators and compare favorably to lifetimes computed from density functional tight binding molecular dynamics calculations. Phase-resolved spectra provided their orientational information. We propose the new spectroscopy as an attractive alternative to time domain vibrational spectroscopy or heterodyne detection schemes for studying vibrational energy relaxation and vibrational coherences in molecules at molecular surfaces or interfaces.

show abstract

Method for Evaluating Vibrational Mode Assignments in Surface-Bound Cyclic Hydrocarbons Using Sum-Frequency Generation

Cited by 18 publications

References 114 publications

Vibrational Sum Frequency Generation Spectroscopy of Secondary Organic Material Produced by Condensational Growth from α-Pinene Ozonolysis

Vibrational Sum Frequency Generation Spectroscopy of Secondary Organic Material Produced by Condensational Growth from α-Pinene Ozonolysis

Towards the identification of molecular constituents associated with the surfaces of isoprene-derived secondary organic aerosol (SOA) particles

Accurate Line Shapes from Sub-1 cm^–1 Resolution Sum Frequency Generation Vibrational Spectroscopy of α-Pinene at Room Temperature

Contact Info

Product

Resources

About

Method for Evaluating Vibrational Mode Assignments in Surface-Bound Cyclic Hydrocarbons Using Sum-Frequency Generation

Cited by 18 publications

References 114 publications

Vibrational Sum Frequency Generation Spectroscopy of Secondary Organic Material Produced by Condensational Growth from α-Pinene Ozonolysis

Vibrational Sum Frequency Generation Spectroscopy of Secondary Organic Material Produced by Condensational Growth from α-Pinene Ozonolysis

Towards the identification of molecular constituents associated with the surfaces of isoprene-derived secondary organic aerosol (SOA) particles

Accurate Line Shapes from Sub-1 cm–1 Resolution Sum Frequency Generation Vibrational Spectroscopy of α-Pinene at Room Temperature

Contact Info

Product

Resources

About

Accurate Line Shapes from Sub-1 cm^–1 Resolution Sum Frequency Generation Vibrational Spectroscopy of α-Pinene at Room Temperature