Low Mole Fractions Research Articles

Modeling the temperature of maximum density of aqueous tert-butanol solutions

Short-chain alcohols at high dilution are among the very few solutes that enhance the anomalous behavior of water, in particular the value of the temperature of maximum density. This peculiar feature, first discovered experimentally in the early twenties, has remained elusive to a full explanation in terms of atomistic models. In this paper, we first introduce a two-site model of tert-butanol in which the interactions involving hydrogen bonding are represented by a Stillinger–Weber potential, following the ideas established by Molinero and Moore (2009) for water. Our model parameters are fit so as to semi-quantitatively reproduce the experimental densities and vaporization enthalpies of previously proposed united atom and all atom OPLS models. Water is represented using the aforementioned potential model introduced by Molinero and Moore, with cross interaction parameters between water and tert-butanol optimized to yield a reasonable description of the experimental excess enthalpies and volumes over the whole composition range of the mixture. We will see that our simple model is able to reproduce the presence of a maximum in the change of the temperature of maximum density for very low alcohol mole fractions, followed by a considerable decrease until the density anomaly itself disappears. We have correlated this behavior with changes in the local structure of water and compared it with the results of all-atom simulations of water/tert-butanol mixtures.

Atmospheric oil and natural gas hydrocarbon trends in the Northern Colorado Front Range are notably smaller than inventory emissions reductions

From 2008 to mid-2016, there was more than a 7-fold increase in oil production and nearly a tripling of natural gas production in the Colorado Denver–Julesburg Basin (DJB). This study utilized air samples collected at the Boulder Atmospheric Observatory (BAO) tower in southwestern Weld County in the DJB to investigate atmospheric mole fraction trends of methane and volatile organic compounds (VOCs). Elevated methane and propane mole fractions and low values (<1) in the ratio of i-pentane to n-pentane at BAO were found to be associated with flow patterns that transport air from the northeast (NE) to east (E) sector to the site, the direction where the primary locations of oil and natural gas (O&NG) extraction and processing activities are located. Median mole fractions of the O&NG tracer propane at BAO were 10 times higher than background values when winds came from the NE quadrant. This contrasts with lower mole fractions of O&NG-related constituents in air parcels arriving at BAO from the south, the direction of the major urban area of Denver. None of O&NG tracers, for example, methane and propane, show statistically significant trends in mole fraction (relative to the background) over the study period in air transported from the DJB. Also, longer term acetylene mole fraction changes were not seen in NE quadrant or south sector samples. A significant decline in the mole fraction ratio of i-pentane to n-pentane in the NE sector data provides evidence of an increasing influence of O&NG on the overall composition of VOCs measured at BAO, a change not seen in measurements from the south (urban) sector. These results suggest that O&NG emissions and resulting atmospheric mole fractions have remained relatively constant over 2008–2016. The behavior in the observations is in contrast to the most recent VOC emissions inventory. While the inventory projects O&NG total VOC emission reductions between 2011 and 2020, of –6.5% per year despite the large production increases, the best estimate of the propane emission rate of change for the DJB-filtered data during 2008–2016 is much smaller, that is, –1.5% per year.

Observation of Net Stimulated Emission in CsPbBr3 Thin Films Prepared by Pulsed Laser Deposition

AbstractInorganic halid perovskites, such as CsPbX3 (X = Br, Cl, or I), have attracted a great deal of attention for next generation on‐chip optoelectronic devices for which high quality thin films are essential. So far, most utilized fabrication techniques for halide perovskite films have been based on solution synthesized methods, taking advantage of cost effectiveness and flexibility. Conventional solution processed thin films suffer from pinholes, poor morphology and/or low mole fraction when embedded in glass or polymer matrixes, unavoidably limiting their application‐level. Herein, we report the fabrication of high crystalline and coverage CsPbBr3 thin films by using a single‐step physical technique – pulsed laser deposition (PLD). As‐fabricated thin films demonstrate stimulated emission with low pump threshold at room temperature. Systematic investigations suggest that the mechanism of stimulated emission in our CsPbBr3 thin films originates from exciton−exciton inelastic scattering. These results not only shed light on high performance all‐inorganic CsPbBr3 perovskite films for various optoelectronic devices, but also enrich the comprehension of stimulated emission mechanism of all‐inorganic CsPbBr3 perovskite materials.

The role of oxygenated species in the growth of graphene, fullerenes and carbonaceous particles

The growth of carbonaceous materials was studied using a Kinetic Monte Carlo model that captures the growth and oxidation of six-member and partially-embedded five-member rings. A novel algorithm was used to resolve the migration of partially-embedded five-member rings. Circumcoronene molecules were grown at 1500 K and 1 atm in the presence of varying mole fractions of atomic and molecular oxygen and constant mole fractions of hydrogen and acetylene. Four regions of carbon growth associated with different carbonaceous products were identified. Graphene was formed in the presence of high mole fractions of atomic oxygen 10−4<XO≤10−2. Fullerenes were formed in the presence of low mole fractions of atomic oxygen and high mole fractions of molecular oxygen (XO ≤ 10−4 and 10−2 < XO2 ≤ 10−1). Low mole fractions of both atomic and molecular oxygen (XO ≤ 10−4 and XO2 ≤ 10−2) resulted in structures that became curved as time progressed. Small structures were found at the highest mole fractions of atomic oxygen (XO > 10−2). The production and consumption of partially-embedded five-member rings appear to explain the formation of the observed structures. The oxidation of partially-embedded five-member rings produces armchair sites that grow to form flat graphenic structures. Formation and subsequent embedding of partially-embedded five-member rings result in curved structures that resemble fullerenes.

Different chemical effect of hydrogen addition on soot formation in laminar coflow methane and ethylene diffusion flames

Previous studies showed that adding hydrogen (H2) can have an opposite chemical effect on soot formation: its chemical effect enhances and suppresses soot formation in methane (CH4) and ethylene (C2H4) diffusion flames, respectively. Such opposite chemical effect of H2 (CE-H2) remains unresolved. The different CE-H2 is studied numerically in the two laminar coflow diffusion flames. A detailed chemical mechanism with the addition of a chemically inert virtual species FH2 is used to model the gas-phase combustion chemistry in this study. Particularly, a reaction pathway analysis was performed based on the numerical results to gain insights into how H2 addition to fuel affects the pathways leading to the formation of benzene (A1) in CH4 and C2H4 flames. The numerical results show that the CE-H2 in CH4 diffusion flame to prompt soot formation is ascribed that the higher mole fraction of H atom promotes the formation of A1 and Acetylene (C2H2) and leads to higher nucleation rate and eventually higher soot surface growth rate. In contrast, adding H2 to C2H4 diffusion flames decreases soot nucleation and surface growth rate. The lower soot nucleation rate is due to the lower mole fractions of pyrene (A4), while the lower soot surface growth rate is due to the lower mole fractions of H atom and C2H2, higher mole fraction of H2 and lower soot nucleation rate. Furthermore, the CE-H2 in C2H4 diffusion flames promotes the formation of A1, but suppresses the formation of A4.

Crosslinking in Semi-Batch Seeded Emulsion Polymerization: Effect of Linear and Non-Linear Monomer Feeding Rate Profiles on Gel Formation.

Waterborne latex is often called a product-of-process. Here, the effect of semi-batch monomer feed rate on the kinetics and gel formation in seeded emulsion polymerization was investigated for the copolymerization of n-butyl methacrylate (n-BMA) and ethylene glycol dimethacrylate (EGDMA). Strikingly, the gel fraction was observed to be significantly influenced by monomer feed rate, even while most of the experiments were performed under so-called starve-fed conditions. More flooded conditions from faster monomer feed rates, including seeded batch reactions, counterintuitively resulted in significantly higher gel fraction. Chain transfer to polymer was intentionally suppressed here via monomer selection so as to focus mechanistic insights to relate only to the influence of a divinyl monomer, as opposed to being clouded by contributions to topology from long chain branching. Simulations revealed that the dominant influence on this phenomenon was the sensitivity of primary intramolecular cyclization to the instantaneous unreacted monomer concentration, which is directly impacted by monomer feed rate. The rate constant for cyclization for these conditions was determined to be first order and 4000 s−1, approximately 4 times that typically observed for backbiting in acrylates. This concept has been explored previously for bulk and solution polymerizations, but not for emulsified reaction environments and especially for the very low mole fraction divinyl monomer. In addition, while gel fraction could be dramatically manipulated by variations in linear monomer feed rates, it could be markedly enhanced by leveraging non-linear feed profiles built from combination sequences of flooded and starved conditions. For a 2 h total feed time, a fully linear profile resulted in 30% gel while a corresponding non-linear profile with an early fast-feed segment resulted in 80% gel.

Modelling and measurements of gas tungsten arc welding in argon–helium mixtures with metal vapour

Argon–helium mixtures in gas tungsten arc welding of an iron workpiece are investigated using an axisymmetric computational model that includes the cathode, workpiece, and arc plasma in the computational domain. The three-gas combined diffusion coefficient method is used to treat diffusion of helium, argon, and iron vapour. Calculations for argon–helium mixtures without metal vapour are performed; good agreement with previous numerical results is found. A transition from a helium-like to an argon-like arc occurs when the argon mole fraction increases above about 0.3. Calculations for a wide range of argon–helium mixtures including iron vapour are then performed. Adding helium to argon alters the arc properties and affects the weld geometry. Iron vapour cools the arc for all argon–helium mixtures. Iron vapour is present above the workpiece, near the cathode and in the arc fringes for very low argon mole fractions. As the argon mole fraction increases, the iron vapour becomes increasingly confined to the region above the workpiece, with small amounts near the cathode tip. Emission spectroscopy measurements of arcs in argon–helium mixtures with water-cooled copper and uncooled iron workpieces were performed. The measured distributions of atomic helium and iron emission show good agreement with the predictions of the model.

Evaluation of the metrological characteristics of Raman analyzer of natural gas

The advantages of the Raman spectroscopy method in comparison with gas chromatography in the analysis of the composition of natural gas are described. The metrological characteristics of a Raman gas analyzer developed at the Institute of Monitoring of Climatic and Ecological Systems of the Siberian Branch of the Russian Academy of Sciences have been studied. A series of measurements were carried out on three natural gas simulators with different concentrations of components. It is shown that Raman gas analyzers are capable of providing high measurement accuracy, close to that of gas chromatographs when analyzing components with a low molar fraction (0.001–0.010 %). It is noted that when analyzing components with a molar fraction in the range of 0.01–100.00 %, the accuracy of the proposed Raman gas analyzer surpassed the accuracy of gas chromatographs.

Excess Molar Volumes of Binary Liquid Mixtures of Ketocyclohexane (C6H10O), + CH2Cl2, +CHCl3, + CH2ClCH2Cl, +CHClCCl2, and + CCl3CH3 at 303.15 K

Excess molar volumes, VE, at T = 303.15 K, have been measured for binary liquid mixtures of ketocyclohexane (C6H10O) + dichloromethane (CH2O2), + trichloromethane (CHCl3), + l,2-dichloroethane (CH2ClCH2Cl), + trichloroethene (CHClCCl2), and + 1,1,1- trichloroethane (CCl3CH3). The values of VE have been fitted in appropriate equations using a least-squares method. VE has been found to be negative throughout the entire range of composition for mixtures of C6H10O + CH2Q2, + CHCl3, + CHClCCl2, and + CCl3CH3. For C6H10O + CH2ClCH2Cl, VE has been found to be positive at lower mole fractions of C6H10O, and negative at higher mole fractions. The results obtained have been discussed from the viewpoint of existence of specific interactions between the components.

Raman spectroscopy and DSC assay of the phase coexistence in binary DMPC/cholesterol multilamellar vesicles

The phospholipid/cholesterol binary model systems are an example of simple models whose structure has caused controversy and genuine interest over many decades. The cornerstone underlying the description of such models is the answer to the question of whether these membranes are separated into coexisting phases or domains. Here, we apply label-free Raman spectroscopy and differential scanning calorimetry (DSC) to verify the phase coexistence in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)/cholesterol binary model. Raman spectra demonstrate the peculiarity at 30% molar fraction of cholesterol. Above this concentration, Raman data demonstrate similar characteristics at T = 291, 298, 303 K. At lower molar fractions, at 303 K, we found the agreement of Raman spectra with the predictions of the lever rule of cholesterol. Taken together, low cooperativity of the transition at 30 mol% and the fulfillment of the lever rule suggest the existence of nanoclusters composed of approximately 4 DMPC and 2 cholesterol molecules. At 298 K, the compliance of the lever rule was found in the range from 0 to 20 mol% of cholesterol. At 291 K, the addition of 5% cholesterol leads to the abrupt change of Raman spectra parameters and their continuous evolution with the further increase of cholesterol molar fraction. It seems that cholesterol plays a twofold role in binary mixtures; it reduces the intermolecular cooperativity and forms clusters whose size and DMPC-to-cholesterol ratio depend on cholesterol concentration and temperature.

Composition-dependent mechanism of formation of γ-Fe2O3/carboxymethylcellulose nanocomposites

The distribution of nanoparticles in the volume of the composite is determined by a ratio between reagents at the stage of synthesis. At low molar fractions of iron in the system, nanoparticles are formed inside the coils of macromolecules, and nanoparticles expand their formation closer to the surface with an increase in the iron fraction. The size of the nanoparticles remains independent of the polymer/iron ratio in the reaction mixture.

A phase change calcium looping thermochemical energy storage system based on CaCO3/CaO-CaCl2

Calcium looping thermal energy storage (CaL-TES) is promising because of its high operating temperature, excellent energy storage density, and low material cost. However, a significant problem with the CaL-TES system is the rapid degradation of CaO. To overcome this degradation problem and also improve the energy storage performance, a novel phase change calcium looping thermal energy storage (PCCaL-TES) process has been developed based on the solid solution system of CaCO3/CaO-CaCl2. In the charging process of the PCCaL-TES system, surplus energy is stored via sensible heat, latent heat, and chemical energy with the calcination and melting of the solid solution CaCO3/CaO-CaCl2. In the discharging process, the carbonation and solidification of CaCO3/CaO-CaCl2 takes place and thus the stored energy is retrieved. Compared to the conventional CaL-TES system, the innovative PCCaL-TES system can help maintain a high activity of CaO over long-term operation due to the enhanced heat and mass transfer in the liquid-state carbonation. In this study, the energy storage performance of PCCaL-TES was assessed using the simulation package Aspen Plus v10. According to the modeling results, the PCCaL-TES system can achieve a round-trip efficiency of up to 49% and an energy storage density of nearly 1.5 GJ/m3, presenting improvements of about 4% and 20%, respectively, compared with the conventional CaL-TES system. Meanwhile, a parametric analysis was carried out to examine the effect of key operating parameters on the system performance of PCCaL-TES. The calculations show that the round-trip efficiency of the PCCaL-TES system can be improved by raising the mole fraction of CaCl2, increasing the carbonator temperature, or employing an optimum carbonator pressure. It was also found that a low mole fraction of CaCl2, a high activity of CaO, or a low temperature of CO2 storage was beneficial to achieving a high energy storage density. Finally, the impact of other operating factors on the round-trip efficiency of PCCaL-TES was summarized in a sensitivity analysis. It revealed the round-trip efficiency of the PCCaL-TES system was dominantly determined by the performance of the CO2 turbine (W-TURB) and compressor (W-COMP), the gas–liquid heat exchanger (HX3) and the exhaust CO2 cooler (CL3).

Size-exclusion chromatography of cellulose: observations on the low-molar-mass fraction

Accurate determination of molar mass distribution for disperse cellulose samples has proved to be a challenging task. While size-exclusion chromatography coupled to multi-angle light scattering (MALS) and differential refractive index (DRI) detectors has become the most commonly used method for molar mass determination of celluloses, this technique suffers low sensitivity at the low-molar mass range. As discussed here, the universal method for accurate molar mass distribution analysis of cellulose samples not exists and thus thorough understanding on the differences of the various methodological approaches is important. In this study, the focus is in the accurate determination of the low-molar mass fraction. The results obtained by combining the two calibration strategies, MALS/DRI for polymeric region of a cellulose sample and conventional calibration for oligomeric region, was compared to the results obtained using only MALS/DRI (with extrapolation of the curve where signal-to-noise of MALS is low). For birch pulp sample, the results from the two approaches were comparable; it should be highlighted, however, that MALS/DRI slightly overestimates the molar masses at the low-molar-mass region.

Dependence on both the hydrocarbon chain length and the hydroxyl group position of the thermophysical properties of N,N-dimethylacetamide with n-alkanol or 2-alkanol

This work reports thermophysical properties measurements of binary mixtures of N,N-dimethylacteamide with 1-pentanol and 2-pentanol. Density, ρ, speed of sound, u, refractive index, nD, and kinematic viscosity,ν, were measured over the whole composition range at the temperatures (283.15, 298.15 and 313.15) K and at atmospheric pressure p = 0.1 MPa. Experimental data were used to calculate the following properties: excess molar volume, VE, excess isentropic compressibility,κSE, refractive index deviation, ΔnD, and viscosity deviation, Δη. These properties were correlated with mole fraction or volume fraction using the Redlich-Kister equation. Excess molar volumes were positive for both mixtures although there are some slight negative VE values for the system containing 1-pentanol at lower temperatures and at lower mole fractions. Refractive index deviation behaviour against composition for (N,N-dimethylacetamide + 1-pentanol) was sigmoidal at lower temperatures and negative at T = 313.15 K, on the other hand ΔnD values are negative for the mixture with 2-pentanol. Excess isentropic compressibilities and viscosity deviations were negative for the two systems. The results obtained were interpreted based on both structural and energetic effects. These results were further compared with our previous results for mixtures containing N,N-dimethylacetamide and several n-alkanols or 2-alkanols in order to understand both the influence of the hydrocarbon chain length and the hydroxyl group position.

An experimental and numerical study of soot formation of laminar coflow H2/C2H4 diffusion flames in O2[sbnd]CO2 atmosphere

The effects of adding H2 to fuel on the formation of soot are studied numerically and experimentally in a laminar coflow C2H4 diffusion flame burning in 30%O2–70%CO2 atmosphere by applying the open source flame code CoFlame and two-dimensional light-of-sight attenuation (2D-LOSA) diagnostic, respectively. H2 and He addition to C2H4 were employed in experiments to discuss the chemical effect of adding H2. An extended ABF mechanism with inclusion of two virtual species fictitious hydrogen (FH2, inert H2) and fictitious carbon dioxide (FCO2, inert CO2) was used to model the gas-phase chemistry and to isolate the chemical effects of H2 and CO2 in numerical calculations. Both numerical and experimental results show that the flame height remains nearly unchanged with addition of H2 and He up to 50%. The chemical effect of both CO2 and H2 suppresses soot loading in all the C2H4 flames investigated. Hydrogen addition to C2H4 increases mole fractions of H and H2, but lowers the mole fractions of C3H3 and polycyclic aromatic hydrocarbons (PAHs) and suppresses soot nucleation directly soot surface growth process indirectly. Carbon dioxide in the oxidizer suppresses soot formation by mainly weakening the soot surface growth process through reducing the H radical concentration and flame temperature and secondarily enhancing the oxidation process due to higher mole fraction of OH. There is a weak chemical coupling effect between H2 in fuel and CO2 in oxidizer to further suppress soot formation. This chemical coupling effect results in a lower mole fraction of H, which in turn reduces both soot nucleation and subsequent growth process through surface reactions.

Influence of intermediate temperature heat release on autoignition reactivity of single-stage ignition fuels with varying octane sensitivity

This study investigates the effects of intermediate temperature heat release (ITHR) on autoignition reactivity of full boiling range gasolines with different octane sensitivity through intake temperature and simulated exhaust gas recirculation (EGR) sweeps in a homogenous charge compression ignition (HCCI) engine. To isolate the ITHR effects, low temperature reactivity was suppressed through the use of high intake temperature and low intake oxygen mole fraction. For quantification of ITHR, a new method was applied to the engine data by examining the maximum value of the second derivative of heat release rate. Combustion phasing comparisons of fuels with octane sensitivity showed that fuel with less octane sensitivity became more reactive as intake temperature and simulated EGR ratio decreased, while fuel with higher octane sensitivity had a reverse trend. For all of the fuels that were tested, the amount of ITHR increased as the intake temperature and oxygen mole fraction increased. These ITHR trends, depending on octane sensitivity, were almost identical with the trends of combustion phasing, showing that ITHR significantly affects fuel autoignition reactivity and determines octane sensitivity.

Comparing multistage liquid–liquid extraction with cold water precipitation for improvement of lignin recovery from deep eutectic solvents

After biomass fractionation using deep eutectic solvents (DES), solvent recovery is an essential step. Recovery of lignin from DES by liquid–liquid extraction (LLX) may provide large energy savings compared to cold water precipitation. Lignin that is dissolved in DES from biomass fractionation is inhomogeneous, meaning it has various fractions with different molar weights and possibly variations in functional group densities. Therefore, it is important to compare recoverability of every lignin fraction by LLX with cold-water precipitation. In this work, the recovery of lignin from a DES comprised of 30 wt% choline chloride and 70 wt% lactic acid was studied. Using as much as 30 wt% choline chloride is beneficial to limit leaching of lactic acid. Three cross-current extractions were performed using 2-MTHF. This method recovered 95% of the lignin fractions around 2000 g/mol and 85% of the lignin fractions around 10,000 g/mol. No inter-aromatic ether bonds were found in the lignin remaining in the DES raffinate by heteronuclear single quantum coherence spectroscopy (HSQC), indicating the remaining lignin in the DES has a highly condensed nature. Cold water precipitation could fully recover the lignin fractions above 4000 g/mol using 3.5 kg water per kg DES. However, only half of the lignin fraction of 1000 g/mol was recovered. Briefly, LLX is more suitable for the recovery of low molar weight fractions, while cold water precipitation is more suitable for the heavy molar weight fractions. For industrial applications, a combination of both approaches is essential for full lignin recovery.

Effect of particle distance on combustion behaviors through 1-D model with Neumann boundary condition

Moderate or intense low oxygen dilution (MILD) combustion is a promising technology for coal utilization due to the uniform heat flux and low NOx emission. In such coal cloud combustion, it is essential to investigate the effect of surrounding particles on the single coal combustion behaviors. In this work, the effect of particle distance on ignition, volatile flame, soot volume fraction and combustion modes are studied through a 1-D model with Neumann boundary condition. For pulverized coal combustion, heterogeneous ignition is dominating rather than homogeneous ignition. When particle number density is small, the ignition time of coal jet is dominated by that of large particles; while when particle number density is large, the ignition time of coal jet is dominated by that of small particles. According to the transient oxygen distribution at different particle distances, when the particle distance is large, the combustion is diffusion controlled; while when the particle distance is small, the combustion is kinetics controlled. At low oxygen mole fraction, soot emission increases with increasing particle distance because the yields-promoting effect dominates. At high oxygen mole fraction, the consumption-strengthening effect competes with the yields-promoting effect, thus the soot emission increases first and then decreases as particle distance increases. The numerical method in this work is able to predict the combustion modes at different particle number density. At least 90 times of the particle diameter is required for the size of the calculating domain when the Dirichlet boundary condition is used for the modeling of a single coal particle combustion.

Experimental investigation of the aluminum combustion in different O2 oxidizing mixtures: Effect of the diluent gases

The existence of different distinct phases during the aluminum combustion process was unambiguously proved and widely discussed in several studies on single burning aluminum particles. Indeed, in the case of a combustion in diffusion vapor phase, the formation of growing aluminum oxide caps on the droplet surface is suspected to drive the transition from a symmetric to an asymmetric regime. Especially based on diverse observations for aluminum particles burning in O2/N2, a hypothesis was proposed on the effect of N2 which probably contributes to the regime transition occurrence. To extend research efforts and get a further understanding of the asymmetric transition development, and, more generally on aluminum combustion, an analysis in O2/N2, O2/Ar and O2/He oxidizing mixtures is presented. This work is based on an advanced experimental technique allowing to levitate a single particle and visualize its self-sustained combustion with high temporal and spatial resolution. Combustion parameters of ignited micron-sized aluminum particles (30–100 µm) at atmospheric pressure were accurately determined using optical diagnostics. Results provide a new quantified dataset and allow to compare the relative effect of N2, Ar and He as diluent gases in the aluminum combustion process. Burning times are found to be similar, regardless of the considered diluent gas, as well as the aluminum consumption rate in symmetric regime. However, estimations on the relative duration of the symmetric phase demonstrate a potential influence of N2 which promotes the regime transition in comparison with Ar and He for low molar fraction of oxidizer. The ratio between flame and droplet diameters is also modified depending on the inert gas and is determined. Observed trends are discussed and compared to available data to improve the description and quantification of the relative influence of the inert gases.

Interaction of Water at the Hydrophobic Interface of Alkyl Group of Alcohol with p‐Nitro‐Aniline Charge Transfer State

AbstractThe evolution of photo‐induced intra molecular charge transfer (ICT) transition energy of p‐nitro‐aniline (PNA), with respect to the mole fraction of alcohol in alcohol water mixture has been used to study, the interaction of hydrophobic hydration ‐shell of linear alcohols with PNA‐ICT state. The linear alcohol ranges from methanol to propanol. The plot of absorption energy of PNA charge transfer transition versus mole fraction of alcohol shows the following features. At lower mole fraction of alcohol, the absorption energy of PNA versus mole‐fraction of alcohol plot at first, decreases below the absorption energy of PNA recorded in pure water and alcohol, goes through a minimum and then increases. Similar behaviour is obtained even after subtracting the contribution from dielectric non‐ideality. The behaviour at lower mole fraction thus indicates the modification of specific interaction of PNA with water due to the presence of alcohol. Further, the absorption energy minimum shifts towards lower mole fraction of alcohol as the chain length of alcohol increases. These results, thus reveals the interaction of PNA with the modified water structure at the hydrophobic interface of alkyl group and supports the current understanding of hydrophobic hydration. To our knowledge, this study for the first time reveals that, hydration shell around hydrophobic group has higher ability to stabilize the PNA‐ICT state by hydrogen bonding interaction compared to bulk water.