Pressure shifts in the vibrational Raman spectra of hydrogen and deuterium, 315–85 K

1978 ◽  
Vol 56 (8) ◽  
pp. 1102-1108 ◽  
Author(s):  
E. C. Looi ◽  
J. C. Stryland ◽  
H. L. Welsh
Keyword(s):  
Standard Deviation ◽  
Raman Spectra ◽  
Rotational Level ◽  
The Other ◽  
Dispersion Forces ◽  
Temperature Dependent ◽  
Vibrational Coupling ◽  
Frequency Shifts ◽  
Linear Coefficient ◽  
Gas Density

The Raman frequencies of the Q(J) lines of the fundamental Raman bands of compressed H2 and D, were measured with a standard deviation of ±0.02 cm−1 at gas densities from 10 to 100 amagat at several temperatures in the range 315 to 85 K. The frequency shifts are negative and linear in the gas density; they range up to −1.2 cm−1 for H2 and −0.7 cm−1 for D2. The linear coefficient for the Q(J) line has the form, ai + ac(nJ/n), where nJ/n is the fractional population of the rotational level, J, and ai and ac are constants independent of J. The constant ai is strongly temperature-dependent and is interpreted as the vibrational shift due to isotropic dispersion and overlap forces. On the other hand, ac is practically temperature-independent and is believed to arise from vibrational coupling through dispersion forces.

VIBRATIONAL FREQUENCY PERTURBATIONS IN THE RAMAN SPECTRUM OF COMPRESSED GASEOUS HYDROGEN

1964 ◽  
Vol 42 (6) ◽  
pp. 1058-1069 ◽  
Author(s):  
A. D. May ◽  
G. Varghese ◽  
J. C. Stryland ◽  
H. L. Welsh
Keyword(s):  
Raman Band ◽  
Intermolecular Forces ◽  
Hydrogen Gas ◽  
High Spectral Resolution ◽  
Intermolecular Potential ◽  
Dispersion Forces ◽  
Frequency Shifts ◽  
Linear Coefficient ◽  
Relative Population ◽  
Good Agreement

The frequencies of the Q(J) lines of the fundamental Raman band of compressed hydrogen gas were measured with high spectral resolution for a series of densities from 25 to 400 Amagat units at 300 °K and 85 °K. The frequency shifts are expressed as a power series in the gas density. The linear coefficient at a given temperature has the form aJ = ai + ae(nJ/n), where ai, constant for all the Q lines, can be interpreted in terms of isotropic intermolecular forces, and ae(nJ/n), proportional to the relative population of the initial J level, arises from the inphase coupled oscillation of pairs of molecules. The temperature variation of ai is analyzed on the basis of the Lennard-Jones intermolecular potential and the molecular pair distribution function. The repulsive overlap forces and the attractive dispersion forces give, respectively, positive and negative contributions to ai, which can be characterized by the empirical parameters Krep and Katt. The values of Katt and ae are in good agreement with calculations based on the polarizability model of the dispersion forces. The relation of the results to the Raman frequency shifts in solid hydrogen is discussed.

THE RAMAN SPECTRA OF LIQUID AND SOLID H2, D2, AND HD AT HIGH RESOLUTION

1962 ◽  
Vol 40 (1) ◽  
pp. 9-23 ◽  
Author(s):  
S. S. Bhatnagar ◽  
Elizabeth J. Allin ◽  
H. L. Welsh
Keyword(s):  
Raman Spectrum ◽  
High Resolution ◽  
Raman Spectra ◽  
Vibrational Frequencies ◽  
Dispersion Forces ◽  
Present Communication ◽  
Linear Dispersion ◽  
Vibrational Coupling

The Raman spectra of liquid (~18° K) and solid (~2° K) n-H2, p-H2, n-D2, o-D2(80%), and HD were photographed with a reciprocal linear dispersion of 3 to 6 cm−1 per mm. The S0 rotational lines show broadening of a few cm−1 but the Q1 vibrational lines are very sharp. The S0(0) transition of p-H2 and o-D2 is a triplet of sharp lines, but the corresponding transition in HD is not split. The vibrational frequencies in the liquid are lowered by 7 to 9 cm−1 and in the solid by 8 to 11 cm−1 from the gas values. The Raman spectrum of p-H2 has been discussed in detail by Van Kranendonk. In the present communication the vibrational shifts in the various solids are correlated by representing them as the sums of shifts due to dispersion forces, overlap forces, and vibrational coupling.

The split-up of G band and 2D band in temperature-dependent Raman spectra of suspended graphene

2021 ◽  
Vol 139 ◽  
pp. 106960 ◽  
Author(s):  
Yi Liu ◽  
Yafang Shi ◽  
Wenguang Zhou ◽  
Wei Shi ◽  
Wei Dang ◽  
...  
Keyword(s):  
Raman Spectra ◽  
Temperature Dependent ◽  
Suspended Graphene

CONFORMATIONAL EQUILIBRIA IN OPEN-CHAIN α,β-UNSATURATED KETONES

1961 ◽  
Vol 39 (11) ◽  
pp. 2225-2235 ◽  
Author(s):  
K. Noack ◽  
R. Norman Jones
Keyword(s):  
Raman Spectra ◽  
Equilibrium Mixture ◽  
Infrared And Raman Spectra ◽  
Temperature Dependent ◽  
Trans Form ◽  
Open Chain ◽  
Unsaturated Ketones ◽  
Conformational Isomers ◽  
Alkyl Substitution ◽  
Conformational Equilibria

The infrared and Raman spectra of trans-Δ3-penten-2-one have been measured over the temperature range +30° to −75° and +85° to +5° respectively. The temperature-dependent changes observed in the spectra indicate that this ketone exists as an equilibrium mixture of s-cis and s-trans conformational isomers in the liquid state. The s-trans form is the more stable and is present exclusively in the crystalline solid.Similar measurements have been carried out on Δ3-buten-2-one. The infrared and Raman spectra of this ketone also exhibit temperature effects that can be explained by a similar equilibrium, though the evidence is not as conclusive as for trans-Δ3-penten-2-one.The influence of alkyl substitution at the α- and β-carbon atoms on the relative stability of the s-cis and s-trans forms of α,β-unsaturated ketones is discussed.

scholarly journals An alternative to the rejection of observations

1932 ◽  
Vol 137 (831) ◽  
pp. 78-87 ◽  
Keyword(s):  
Standard Deviation ◽  
Continuous Function ◽  
Large Deviations ◽  
Opposite Direction ◽  
Standard Error ◽  
The Other ◽  
Cause Of Error ◽  
The Mean ◽  
Normal Law ◽  
Usual Rule

1. It is widely felt that any method of rejecting observations with large deviations from the mean is open to some suspicion. Suppose that by some criterion, such as Peirce’s and Chauvenet’s, we decide to reject observations with deviations greater than 4 σ, where σ is the standard error, computed from the standard deviation by the usual rule; then we reject an observation deviating by 4·5 σ, and thereby alter the mean by about 4·5 σ/ n , where n is the number of observations, and at the same time we reduce the computed standard error. This may lead to the rejection of another observation deviating from the original mean by less than 4 σ, and if the process is repeated the mean may be shifted so much as to lead to doubt as to whether it is really sufficiently representative of the observations. In many cases, where we suspect that some abnormal cause has affected a fraction of the observations, there is a legitimate doubt as to whether it has affected a particular observation. Suppose that we have 50 observations. Then there is an even chance, according to the normal law, of a deviation exceeding 2·33 σ. But a deviation of 3 σ or more is not impossible, and if we make a mistake in rejecting it the mean of the remainder is not the most probable value. On the other hand, an observation deviating by only 2 σ may be affected by an abnormal cause of error, and then we should err in retaining it, even though no existing rule will instruct us to reject such an observation. It seems clear that the probability that a given observation has been affected by an abnormal cause of error is a continuous function of the deviation; it is never certain or impossible that it has been so affected, and a process that completely rejects certain observations, while retaining with full weight others with comparable deviations, possibly in the opposite direction, is unsatisfactory in principle.

Extensional flows with viscous heating

2007 ◽  
Vol 571 ◽  
pp. 359-370 ◽  
Author(s):  
JONATHAN J. WYLIE ◽  
HUAXIONG HUANG
Keyword(s):  
Critical Value ◽  
The Other ◽  
Viscous Heating ◽  
Constant Force ◽  
Temperature Dependent ◽  
Downstream Location ◽  
Temperature Dependent Viscosity ◽  
Pulling Forces ◽  
Extensional Flows ◽  
Dependent Viscosity

In this paper we investigate the role played by viscous heating in extensional flows of viscous threads with temperature-dependent viscosity. We show that there exists an interesting interplay between the effects of viscous heating, which accelerates thinning, and inertia, which prevents pinch-off. We first consider steady drawing of a thread that is fed through a fixed aperture at given speed and pulled with a constant force at a fixed downstream location. For pulling forces above a critical value, we show that inertialess solutions cannot exist and inertia is crucial in controlling the dynamics. We also consider the unsteady stretching of a thread that is fixed at one end and pulled with a constant force at the other end. In contrast to the case in which inertia is neglected, the thread will always pinch at the end where the force is applied. Our results show that viscous heating can have a profound effect on the final shape and total extension at pinching.

scholarly journals An Optimal and Stable Algorithm for Clustering Numerical Data

Algorithms ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 197
Author(s):  
Ali Seman ◽  
Azizian Mohd Sapawi
Keyword(s):  
Standard Deviation ◽  
Real World ◽  
Clustering Algorithm ◽  
Numerical Data ◽  
Zero Point ◽  
The Other ◽  
Suitable Alternative ◽  
Stable Algorithm ◽  
Real World Applications

In the conventional k-means framework, seeding is the first step toward optimization before the objects are clustered. In random seeding, two main issues arise: the clustering results may be less than optimal and different clustering results may be obtained for every run. In real-world applications, optimal and stable clustering is highly desirable. This report introduces a new clustering algorithm called the zero k-approximate modal haplotype (Zk-AMH) algorithm that uses a simple and novel seeding mechanism known as zero-point multidimensional spaces. The Zk-AMH provides cluster optimality and stability, therefore resolving the aforementioned issues. Notably, the Zk-AMH algorithm yielded identical mean scores to maximum, and minimum scores in 100 runs, producing zero standard deviation to show its stability. Additionally, when the Zk-AMH algorithm was applied to eight datasets, it achieved the highest mean scores for four datasets, produced an approximately equal score for one dataset, and yielded marginally lower scores for the other three datasets. With its optimality and stability, the Zk-AMH algorithm could be a suitable alternative for developing future clustering tools.

Preparation of Graphene/MoS2 Composite for Detection of Dopamine

2022 ◽  
Vol 905 ◽  
pp. 192-197
Author(s):  
Lin Lin Cai ◽  
Xiao Qing Jiang
Keyword(s):  
Raman Spectra ◽  
Photoelectron Spectroscopy ◽  
The Other ◽  
Organic Salt ◽  
Carbon Electrode ◽  
Sodium Tartrate ◽  
X Ray ◽  
Transmission Electron ◽  
Linear Detection ◽  
Potassium Sodium Tartrate

A new composite of graphene/MoS2 is synthesized by co-exfoliation of graphite and MoS2 in isopropanol (IPA) using the organic salt potassium sodium tartrate as the assistant. The composite is characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Raman spectra. The results of TEM, XPS, and Raman spectra all illustrate that the graphene/MoS2 composite has been synthesized successfully. Furthermore, the composite is modified on glassy carbon electrode to fabricate a sensor to detect dopamine (DA). The sensor shows two linear detection ranges for DA. One is 1-45 μM and the other is 45-120 μΜ. The detection limit of the sensor (S/N=3) is 0.76 μM.

Daily fluctuations in aircraft noise exposure around civil airports and military airfields in Japan

2021 ◽  
Vol 263 (1) ◽  
pp. 5154-5160
Author(s):  
Koichi Makino ◽  
Naoaki Shinohara
Keyword(s):  
Standard Deviation ◽  
Noise Exposure ◽  
Quality Standards ◽  
Sound Level ◽  
Aircraft Noise ◽  
The Other ◽  
Yearly Average ◽  
Daily Total ◽  
Airline Flight ◽  
Monitoring Stations

In Japan, yearly average of (day-evening-night sound level) as cumulative noise index has been adopted in national noise guideline of "Environmental Quality Standards for Aircraft Noise." Daily flight movements at civil airports are almost stable because of scheduled airline flight. On the other, daily total flight movements at military airfields greatly change day to day because of training flights, etc. Thus, noise exposure around the airport may change significantly from day to day due to change of flight movement. This paper shows examples of fluctuations, frequency distribution and deviation of daily using aircraft noise monitoring data around civil airports and military airfields. In the case of civil airports, standard deviation of daily was less than 5 dB at the monitoring stations where the yearly average of were about 55 dB or more. However, the standard deviation of daily increased 10 dB or more in some cases at points where yearly average of less than 55 dB. Furthermore, in the case of military airfields, the standard deviation of daily were 5 dB or more for all monitoring stations.

scholarly journals Nature versus Nurture in Shallow Convection

2010 ◽  
Vol 67 (5) ◽  
pp. 1655-1666 ◽  
Author(s):  
David M. Romps ◽  
Zhiming Kuang
Keyword(s):  
Standard Deviation ◽  
The Other ◽  
Cloud Base ◽  
Shallow Convection ◽  
Eddy Simulation ◽  
Cloud Properties ◽  
Nature Versus Nurture ◽  
Large Eddy ◽  
The Mean ◽  
Single Set

Abstract Tracers are used in a large-eddy simulation of shallow convection to show that stochastic entrainment (and not cloud-base properties) determines the fate of convecting parcels. The tracers are used to diagnose the correlations between a parcel’s state above the cloud base and both the parcel’s state at the cloud base and its entrainment history. The correlation with the cloud-base state goes to zero a few hundred meters above the cloud base. On the other hand, correlations between a parcel’s state and its net entrainment are large. Evidence is found that the entrainment events may be described as a stochastic Poisson process. A parcel model is constructed with stochastic entrainment that is able to replicate the mean and standard deviation of cloud properties. Turning off cloud-base variability has little effect on the results, which suggests that stochastic mass-flux models may be initialized with a single set of properties. The success of the stochastic parcel model suggests that it holds promise as the framework for a convective parameterization.

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