Ultraviolet-C Photoresponsivity Using Fabricated TiO2 Thin Films and Transimpedance-Amplifier-Based Test Setup.

We report on fabricated titanium dioxide (TiO2) thin films along with a transimpedance amplifier (TIA) test setup as a photoconductivity detector (sensor) in the ultraviolet-C (UV-C) wavelength region, particularly at 260 nm. TiO2 thin films deposited on high-resistivity undoped silicon-substrate at thicknesses of 100, 500, and 1000 nm exhibited photoresponsivities of 81.6, 55.6, and 19.6 mA/W, respectively, at 30 V bias voltage. Despite improvements in the crystallinity of the thicker films, the decrease in photocurrent, photoconductivity, photoconductance, and photoresponsivity in thicker films is attributed to an increased number of defects. Varying the thickness of the film can, however, be leveraged to control the wavelength response of the detector. Future development of a chip-based portable UV-C detector using TiO2 thin films will open new opportunities for a wide range of applications.

Ultra-thin films of amphiphilic lanthanide complexes: multi-colour emission from molecular monolayers.

We report the synthesis and Langmuir-Blodgett deposition of 4 brightly emissive lanthanide amphiphiles that can be co-deposited to give multi-emissive ultra-thin films where two, three and four distinct lanthanide emission profiles are observed. To the best of our knowledge, this is the first report of a four-component emissive Langmuir-Blodgett film.

Strong, Nonresonant Radiation Enhances Cis-Trans Photoisomerization of Stilbene in Solution.

Previously, it has been demonstrated that external electric fields may be used to exert control over chemical reactivity. In this study, the impact of a strong, nonresonant IR field (1064 nm) on the photoisomerization of cis-stilbene is investigated in cyclohexane solution. The design of a suitable reaction vessel for characterization of this effect is presented. The electric field supplied by the pulsed, near-IR radiation (εl = 4.5 × 107 V/cm) enhances the cis → trans photoisomerization yield at the red edge of the absorption spectrum (wavelengths between 337 and 340 nm). Within the microliter focal volume, up to 75% of all cis-stilbene molecules undergo isomerization to trans-stilbene in the strong electric-field environment, indicating a significant increase relative to the 35% yield of trans-stilbene under field-free conditions. This result correlates with a 1-3% enhancement in the trans-stilbene concentration throughout the bulk solution. Theoretical analysis suggests that the observed change is the result of dynamic Stark shifting of the ground and first excited states, leading to a significant redshift in cis-stilbene's absorption spectrum. The predicted increase in the absorption cross section in this range of excitation wavelengths is qualitatively consistent with the experimental increase in trans-stilbene production.

Excess N2 and denitrification in hyporheic porewaters and groundwaters of the San Joaquin River, California.

The San Joaquin River (SJR) in California is purported to receive high nitrate loadings from surrounding agricultural lands through both surface and groundwater inputs. To investigate the potential removal of nitrate (NO3-) from surface and ground water sources, the spatial variations in dinitrogen (N2) gas concentrations and direct measurements of sediment denitrification potential (DNP), with amended NO3- and carbon (C) treatments, were investigated in the summer along a 95-km reach of the San Joaquin River. Excess N2 in hyporheic porewaters ranged from <0.1 to 8.65 mg L-1 and was significantly higher in porewaters from the 1.3 m (ground water source) versus 0.3 m (mixed surface and ground water) depths. In deep groundwater wells (3-7 m), median excess N2 concentration was 5.39 mg L-1 (range = <0.1-14.6 mg L-1). Excess N2 concentrations were inversely correlated with dissolved oxygen and NO3- concentrations suggesting denitrification as an important process in the dominantly anaerobic sediments. Hyporheic porewater NO3- concentrations exceeded the detection limit of 0.01 mg L-1 in only 20% of the hyporheic porewaters, in spite of high NO3- concentrations measured in both surface waters (mean = 2.25 mg N L-1) and surrounding groundwaters. Sediment DNP rates averaged 253 and 297 µg N kg-1 hr-1 for NO3- amended, and NO3- + C amended sediments, respectively, supporting the prevalence of denitrification in hyporheic sediments. Our results indicate that the hyporheic/riparian zones act as an anoxic barrier to nitrate transport from regional groundwater and as a location to remove NO3- from surface waters exchanging with the hyporheic zone.

The U.S. consumer phosphorus footprint: where do nitrogen and phosphorus diverge?

Phosphorus (P) and nitrogen (N) are essential nutrients for food production but their excess use in agriculture can have major social costs, particularly related to water quality degradation. Nutrient footprint approaches estimate N and P release to the environment through food production and waste management and enable linking these emissions to particular consumption patterns. Following an established method for quantifying a consumer-oriented N footprint for the United States (U.S.), we calculate an analogous P footprint and assess the N:P ratio across different stages of food production and consumption. Circa 2012, the average consumer's P footprint was 4.4 kg P capita-1 yr-1 compared to 22.4 kg N capita-1 yr-1 for the food portion of the N footprint. Animal products have the largest contribution to both footprints, comprising >70% of the average per capita N and P footprints. The N:P ratio of environmental release based on virtual nutrient factors (kilograms N or P per kilogram of food consumed) varies considerably across food groups and stages. The overall N:P ratio of the footprints was lower (5.2 by mass) than for that of U.S. food consumption (8.6), reinforcing our finding that P is managed less efficiently than N in food production systems but more efficiently removed from wastewater. While strategies like reducing meat consumption will effectively reduce both N and P footprints by decreasing overall synthetic fertilizer nutrient demands, consideration of how food production and waste treatment differentially affect N and P releases to the environment can also inform eutrophication management.

Where Have All the Nutrients Gone? Long-Term Decoupling of Inputs and Outputs in the Willamette River Watershed, Oregon, United States.

Better documentation and understanding of long-term temporal dynamics of nitrogen (N) and phosphorus (P) in watersheds is necessary to support effective water quality management, in part because studies have identified time lags between terrestrial nutrient balances and water quality. We present annual time series data from 1969 to 2012 for terrestrial N and P sources and monthly data from 1972 to 2013 for river N and P for the Willamette River Basin, Oregon, United States. Inputs to the watershed increased by factors of 3 for N and 1.2 for P. Synthetic fertilizer inputs increased in total and relative importance over time, while sewage inputs decreased. For N, increased fertilizer application was not matched by a proportionate increase in crop harvest; N use efficiency decreased from 69% to 38%. P use efficiency increased from 52% to 67%. As nutrient inputs to terrestrial systems increased, river concentrations and loads of total N, total P, and dissolved inorganic P decreased, and annual nutrient loads were strongly related to discharge. The N:P ratio of both sewage and fertilizer doubled over time but there was no similar trend in riverine export; river N:P concentrations declined dramatically during storms. River nutrient export over time was related to hydrology and waste discharge, with relatively little influence of watershed balances, suggesting that accumulation within soils or groundwater over time is mediating watershed export. Simply managing yearly nutrient balances is unlikely to improve water quality; rather, many factors must be considered, including soil and groundwater storage capacity, and gaseous loss pathways.

Nonresonant Photons Catalyze Photodissociation of Phenol.

Phenol represents an ideal polyatomic system for demonstrating photon catalysis because of its large polarizability, well-characterized excited-state potential energy surfaces, and nonadiabatic dissociation dynamics. A nonresonant IR pulse (1064 nm) supplies a strong electric field (4 × 107 V/cm) during the photolysis of isolated phenol (C6H5OH) molecules to yield C6H5O + H near two known energetic thresholds: the S1/S2 conical intersection and the S1 - S0 origin. H-atom speed distributions show marked changes in the relative contributions of dissociative pathways in both cases, compared to the absence of the nonresonant IR pulse. Results indicate that nonresonant photons lower the activation barrier for some pathways relative to others by dynamically Stark shifting the excited-state potential energy surfaces rather than aligning molecules in the strong electric field. Theoretical calculations offer support for the experimental interpretation.

Effects of an Experimental Water-level Drawdown on Methane Emissions from a Eutrophic Reservoir.

Reservoirs are a globally significant source of methane (CH4) to the atmosphere. However, emission rate estimates may be biased low due to inadequate monitoring during brief periods of elevated emission rates (that is, hot moments). Here we investigate CH4 bubbling (that is, ebullition) during periods of falling water levels in a eutrophic reservoir in the Midwestern USA. We hypothesized that periods of water-level decline trigger the release of CH4-rich bubbles from the sediments and that these emissions constitute a substantial fraction of the annual CH4 flux. We explored this hypothesis by monitoring CH4 ebullition in a eutrophic reservoir over a 7-month period, which included an experimental water-level drawdown. We found that the ebullitive CH4 flux rate was among the highest ever reported for a reservoir (mean = 32.3 mg CH4 m-2 h-1). The already high ebullitive flux rates increased by factors of 1.4-77 across the nine monitoring sites during the 24-h experimental water-level drawdown, but these emissions constituted only 3% of the CH4 flux during the 7-month monitoring period due to the naturally high ebullitive CH4 flux rates that persist throughout the warm weather season. Although drawdown emissions were found to be a minor component of annual CH4 emissions in this reservoir, our findings demonstrate a link between water-level change and CH4 ebullition, suggesting that CH4 emissions may be mitigated through water-level management in some reservoirs.

Chasing the agostic interaction in ligand assisted cyclometallation reactions of palladium(ii).

A 500 MHz NMR study of the reaction between 1-tetralone oxime and PdCl42- in CD3OD shows resonances attributable to a potential agostic intermediate prior to the formation of the insoluble cyclopalladated product which itself was characterised by X-ray crystallography. Calculated structural, spectroscopic, QTAIM, NBO and NCI analysis results obtained from density functional theory (DFT) calculations give a full description of the putative agostic intermediate [PdCl2(1-tetralone oxime)] (1) which is shown to include a previously unrecognised π-electron density donation from the aromatic ring to the metal in close proximity to the agostic carbon atom. Changing the (N)-OH donor to (N)-OMe does not effect the magnitude of these interactions. (N)-OH and (N)-OMe acetophenone imines in which the aromatic ring has the potential to rotate show similar agostic and π-electron donation to the alicyclic ring counterparts. 1-Tetralone which coordinates to the metal by a Pd-O bond that is much weaker than the Pd-N complexes has a slightly stronger agostic component and slightly weaker π-electron donation than the oxime counterpart.

Linking terrestrial phosphorus inputs to riverine export across the United States.

Humans have greatly accelerated phosphorus (P) flows from land to aquatic ecosystems, causing eutrophication, harmful algal blooms, and hypoxia. A variety of statistical and mechanistic models have been used to explore the relationship between P management on land and P losses to waterways, but our ability to predict P losses from watersheds often relies on small scale catchment studies, where detailed measurements can be made, or global scale models that that are often too coarse-scaled to be used directly in the management decision-making process. Here we constructed spatially explicit datasets of terrestrial P inputs and outputs across the conterminous U.S. (CONUS) for 2012. We use this dataset to improve understanding of P sources and balances at the national scale and to investigate whether well-standardized input data at the continental scale can be used to improve predictions of hydrologic P export from watersheds across the U.S. We estimate that in 2012 agricultural lands received 0.19 Tg more P as fertilizer and confined manure than was harvested in major crops. Approximately 0.06 Tg P was lost to waterways as sewage and detergent nationally based on per capita loads in 2012. We compared two approaches for calculating non-agricultural P waste export to waterways, and found that estimates based on per capita P loads from sewage and detergent were 50% greater than Discharge Monitoring Report Pollutant Loading Tool. This suggests that the tool is likely underestimating P export in waste the CONUS scale. TP and DIP concentrations and TP yields were generally correlated more strongly with runoff than with P inputs or P balances, but even the relationships between runoff and P export were weak. Including P inputs as independent variables increased the predictive capacity of the best-fit models by at least 20%, but together inputs and runoff explained 40% of the variance in P concentration and 46-54% of the variance in P yield. By developing and applying a high-resolution P budget for the CONUS this study confirms that both hydrology and P inputs and sinks play important roles in aquatic P loading across a wide range of environments.

New complexity for aromatic ring agostic interactions.

Density functional theory (DFT) calculations reveal that for ligand directed aromatic ring C-H bond activation, the agostic donation can share the same antibonding acceptor orbitals as a previously unrecognised π-donation from the aromatic ring of the ligand. The recognition of carbon based orbitals assisting the agostic interaction has significant implication for C-H bond activation chemistry.

Reservoir Water-Level Drawdowns Accelerate and Amplify Methane Emission.

Water-level fluctuations due to reservoir management could substantially affect the timing and magnitude of reservoir methane (CH4) fluxes to the atmosphere. However, effects of such fluctuations on CH4 emissions have received limited attention. Here we examine CH4 emission dynamics in six Pacific Northwest U.S. reservoirs of varying trophic status, morphometry, and management regimes. In these systems, we show that water-level drawdowns can, at least temporarily, greatly increase per-area reservoir CH4 fluxes to the atmosphere, and can account for more than 90% of annual reservoir CH4 flux in a period of just a few weeks. Reservoirs with higher epilimnetic [chlorophyll a] experienced larger increases in CH4 emission in response to drawdown (R2 = 0.84, p < 0.01), suggesting that eutrophication magnifies the effect of drawdown on CH4 emission. We show that drawdowns as small as 0.5 m can stimulate ebullition events. Given that drawdown events of this magnitude are quite common in reservoirs, our results suggest that this process must be considered in sampling strategies designed to characterize total CH4 fluxes from reservoirs. The extent to which (and the mechanisms by which) drawdowns short-circuit connections between methanogenesis and methanotrophy, thereby increasing net CH4 fluxes to the atmosphere, should be a focus of future work.

Alternative futures of dissolved inorganic nitrogen export from the Mississippi River Basin: influence of crop management, atmospheric deposition, and population growth.

Nitrogen (N) export from the Mississippi River Basin contributes to seasonal hypoxia in the Gulf of Mexico (GOM). We explored monthly dissolved inorganic N (DIN) export to the GOM for a historical year (2002) and two future scenarios (year 2022) by linking macroeonomic energy, agriculture market, air quality, and agriculture land management models to a DIN export model. Future scenarios considered policies aimed at encouraging bioenergy crop production and reducing atmospheric N-emissions, as well as the effect of population growth and the states' infrastructure plans on sewage fluxes. Model-derived DIN export decreased by about 9% (from 279 to 254 kg N km-2 year-1) between 2002 and 2022 due to a 28% increase in area planted with corn, 24% improvement in crop N-recovery efficiency (NRE, to 0.52), 22% reduction in atmospheric N deposition, and 23% increase in sewage inputs. Changes in atmospheric and sewage inputs had a relatively small effect on DIN export and the effect of bioenergy crop production depended on nutrient management practices. Without improved NRE, increased production of corn would have increased DIN export by about 14% (to 289 kg N km-2 year-1) between 2002 and 2022. Model results suggest that meeting future crop demand while reducing the areal extent of hypoxia could require aggressive actions, such improving basin-level crop NRE to 0.62 or upgrading N-removal capabilities in waste water treatment plants beyond current plans. Tile-drained cropland could contribute up to half of DIN export; thus, practices that reduce N losses from tile drains could also have substantial benefit.

Greenhouse Gas Emissions from Reservoir Water Surfaces: A New Global Synthesis.

Collectively, reservoirs created by dams are thought to be an important source of greenhouse gases (GHGs) to the atmosphere. So far, efforts to quantify, model, and manage these emissions have been limited by data availability and inconsistencies in methodological approach. Here, we synthesize reservoir CH4, CO2, and N2O emission data with three main objectives: (1) to generate a global estimate of GHG emissions from reservoirs, (2) to identify the best predictors of these emissions, and (3) to consider the effect of methodology on emission estimates. We estimate that GHG emissions from reservoir water surfaces account for 0.8 (0.5-1.2) Pg CO2 equivalents per year, with the majority of this forcing due to CH4. We then discuss the potential for several alternative pathways such as dam degassing and downstream emissions to contribute significantly to overall emissions. Although prior studies have linked reservoir GHG emissions to reservoir age and latitude, we find that factors related to reservoir productivity are better predictors of emission.

Future riverine nitrogen export to coastal regions in the United States: prospects for improving water quality.

Nitrogen (N) fluxes generated by an increasing human population have the potential to increase coastal riverine N loading, with implications for areas already degraded by elevated nutrient loads. Here we examine contemporary (year 2005) and future (year 2030) loading of total dissolved N (TDN) in the continental United States using the Nutrient Export from WaterSheds model (NEWS2-TDN). Model-derived TDN estimates compared well with measured export of 29 catchments that represent 65% of land surface area for the continental United States (Nash-Sutcliffe efficiency = 0.83). Future output is based on scenarios that reflect future population growth and "business as usual" (BAU) and "ambitious" (AMB) approaches to nutrient management. Model-derived TDN export was 2.1 Tg N yr in 2005 and 2.2 and 1.6 Tg N yr in 2030 for the BAU and AMB scenarios, respectively. Depending on year and scenario, agriculture supplies 44 to 48% of coastal TDN, atmospheric N deposition supplies 14 to 17%, human sewage supplies 13 to 18%, and background sources supply 21 to 29%. The AMB scenario suggests that reducing nutrient loads to coastal areas will require aggressive actions, including a 25% improvement in agricultural nutrient use efficiency, a 20% reduction in N runoff from croplands, a 30% reduction in ammonia emissions from agriculture, and a 40% reduction in nitrogen oxide emissions from vehicles. Together, these aggressive actions could reduce year 2030 TDN export by 24% from 2005 levels, even with a 20% larger population.

Gopher mounds decrease nutrient cycling rates and increase adjacent vegetation in volcanic primary succession.

Fossorial mammals may affect nutrient dynamics and vegetation in recently initiated primary successional ecosystems differently than in more developed systems because of strong C and N limitation to primary productivity and microbial communities. We investigated northern pocket gopher (Thomomys talpoides) effects on soil nutrient dynamics, soil physical properties, and plant communities on surfaces created by Mount St. Helens' 1980 eruption. For comparison to later successional systems, we summarized published studies on gopher effects on soil C and N and plant communities. In 2010, 18 years after gopher colonization, we found that gophers were active in ~2.5% of the study area and formed ~328 mounds ha(-1). Mounds exhibited decreased species density compared to undisturbed areas, while plant abundance on mound margins increased 77%. Plant burial increased total soil carbon (TC) by 13% and nitrogen (TN) by 11%, compared to undisturbed soils. Mound crusts decreased water infiltration, likely explaining the lack of detectable increases in rates of NO3-N, NH4-N or PO4-P leaching out of the rooting zone or in CO2 flux rates. We concluded that plant burial and reduced infiltration on gopher mounds may accelerate soil carbon accumulation, facilitate vegetation development at mound edges through resource concentration and competitive release, and increase small-scale heterogeneity of soils and communities across substantial sections of the primary successional landscape. Our review indicated that increases in TC, TN and plant density at mound margins contrasted with later successional systems, likely due to differences in physical effects and microbial resources between primary successional and older systems.

Identification of non-classical C-H···M interactions in early and late transition metal complexes containing the CH(ArO)3 ligand.

The fully optimised DFT structure of the d(0) complex [{CH(ArO)3}Ti(NEt2)] (2) at the B3LYP level compares well with the distorted tetrahedral geometry shown by the X-ray crystal structure. QTAIM analysis of the electron density associated with the C-H···Ti interaction shows a well defined bond critical point, a bond path between the hydrogen and titanium centres and a negative value for the energy density indicative of covalency. A natural bond orbital (NBO) picture of the interaction shows that the C-H σ bond electron density donates to a d hybrid orbital on the metal in a linear fashion. Calculated IR and NMR data for the components of the interaction are consistent with experiment. The computed structures for [{CH(ArO)3}Ti(OPh)] (3), [{CH(ArO)3}Zr(NEt2)] (4), [{CH(ArO)3}Hf(NEt2)] (5), show tetrahedral geometries and QTAIM and NBO properties similar to (2). [{CH(ArO)3}Mo(NEt2)] (6) shows distortion of the tripodal ligand and a reduced C-H···M bond angle with properties more consistent with a C-H···M side-on donor interaction. In [{CH(ArO)3}Fe(NEt2)] (7) the C-H···M bond angle is linear and involves a donor interaction. An energy minimised structure maintaining the three fold coordination to the tripodal ligand was not obtained for [{CH(ArO)3}Ni(NEt2)](2-) but changing from a diethyl amide ligand to phenolato gave energy minimised [{CH(ArO)3}Ni(OPh)](2-) (8). This structure shows a distorted square planar geometry with a substantially bent phenoxo ligand and a near linear C-H···M covalent interaction with donor and back bonding properties. The work shows that linear C-H···M interactions can have both agostic and weak hydrogen bond-like covalency.

Communication: transfer of more than half the population to a selected rovibrational state of H2 by Stark-induced adiabatic Raman passage.

By using Stark-induced adiabatic Raman passage (SARP) with partially overlapping nanosecond pump (532 nm) and Stokes (683 nm) laser pulses, 73% ± 6% of the initial ground vibrational state population of H(2) (v = 0, J = 0) is transferred to the single vibrationally excited eigenstate (v = 1, J = 0). In contrast to other Stark chirped Raman adiabatic passage techniques, SARP transfers population from the initial ground state to a vibrationally excited target state of the ground electronic surface without using an intermediate vibronic resonance within an upper electronic state. Parallel linearly polarized, co-propagating pump and Stokes laser pulses of respective durations 6 ns and 4.5 ns, are combined with a relative delay of ~4 ns before orthogonally intersecting the molecular beam of H(2). The pump and Stokes laser pulses have fluences of ~10 J/mm(2) and ~1 J/mm(2), respectively. The intense pump pulse generates the necessary sweeping of the Raman resonance frequency by ac (second-order) Stark shifting the rovibrational levels. As the frequency of the v = 0 → v = 1 Raman transition is swept through resonance in the presence of the strong pump and the weaker delayed Stokes pulses, the population of (v = 0, J = 0) is coherently transferred via an adiabatic passage to (v = 1, J = 0). A quantitative measure of the population transferred to the target state is obtained from the depletion of the ground-state population using 2 + 1 resonance enhanced multiphoton ionization (REMPI) in a time-of-flight mass spectrometer. The depletion is measured by comparing the REMPI signal of (v = 0, J = 0) at Raman resonance with that obtained when the Stokes pulse is detuned from the Stark-shifted Raman resonance. No depletion is observed with either the pump or the Stokes pulses alone, confirming that the measured depletion is indeed caused by the SARP-induced population transfer from the ground to the target state and not by the loss of molecules from photoionization or photodissociation. The two-photon resonant UV pulse used for REMPI detection is delayed by 20 ns with respect to the pump pulse to avoid the ac Stark shift originating from the pump and Stokes laser pulses. This experiment demonstrates the feasibility of preparing a large ensemble of isolated molecules in a preselected single quantum state without requiring an intermediate vibronic resonance.

Analysis of M···H-Si interactions in [{M(CpSiMe2H)Cl3}2], (M = Zr, Hf, Ti and Mo) complexes.

For the d(0) complex [{Zr(CpSiMe(2)H)Cl(3)}(2)] which contains a linear Si-H···Zr interaction across the dimer, DFT calculations are in good agreement with X-ray structures. The BP86 functional shows a slightly stronger interaction than B3LYP but for qualitative purposes either functional is sufficient. QTAIM analysis shows a bond critical point (bcp) for the interaction, a small negative value for the total energy density [H((r))] and the H atomic basin decreases in energy, E(H), and atomic volume compared to the free ligand. NBO analysis showed E(2) for Si-H σ to Zr(dz(2)) donation at 42.8 kcal mol(-1) and a 34% spatial overlap for the interaction consistent with an inverse hydrogen bond. The Wiberg bond index for the interaction is 0.1735 (0.7205 for the Si-H bond), ν((Si-H)) and (1)J((Si-H)) at 2060 cm(-1) and 145.4 Hz compared to 2183 cm(-1) and 172.1 Hz in the free ligand. Using a "synthesis by computation" approach to forming like complexes, similar features were found for [{Hf(CpSiMe(2)H)Cl(3)}(2)]. The titanium complex [{Ti(CpSiMe(2)H)Cl(3)}(2)] does not contain any Si-H···Ti interaction as rotation about the C-Si bond of the ligand occurs to place the Si-H bond hydrogen closer to a terminal chloro ligand across the dimer. An increase in electron density on the metal in the d(2) complex [{Mo(CpSiMe(2)H)Cl(3)}(2)] results in a stronger interaction with a distinct QTAIM analysis bcp [ρ((r)) 0.0448 a.u.], a small negative value for H((r)) and a much reduced H atomic volume. NBO analysis shows E(2) for Si-H σ to Mo(dz(2)) donation at 143.1 kcal mol(-1) and a 29% spatial overlap. Mo(dz(2)) to Si-H σ* donation (back donation) is minimal [E(2) 1.3 kcal mol(-1), ~1% spatial overlap]. The Wiberg bond index is 0.3114 (0.5667 for the Si-H bond), ν((Si-H)) 2015 cm(-1) and (1)J((Si-H)) 120.6 Hz.