물리분석실험 Raman Spectroscopy 결과 레포트

문서 내 토픽

1. Raman Spectroscopy

본 실험에서는 Raman spectroscopy를 이용해 1,2-dicholroethane의 staggered form의 두가지 형태인 anti, gauche form의 각 온도에서의 population 비율을 확인하고 이 변화를 이용해 두 form 사이의 에너지 차이를 측정한다. 에너지 차이를 측정하기 위해서는 시료를 여러 온도에서 raman spectroscopy로 측정해 봐야한다. 본 실험에서는 각각 얼음, dry ice를 가했을 때, Real Temperature로 온도를 나누어서 측정을 진행했다. 각 온도에서 샘플의 raman spectroscopy 측정은 12번 진행되었고 이를 바탕으로 각 온도에서의 두 form 사이의 population 비율을 spectrum 상의 peak 넓이를 통해 구해낸다.
2. 1,2-dichloroethane

본 실험에서는 Raman spectroscopy를 이용해 1,2-dicholroethane의 staggered form의 두가지 형태인 anti, gauche form의 각 온도에서의 population 비율을 확인하고 이 변화를 이용해 두 form 사이의 에너지 차이를 측정한다.
3. Anti and Gauche Forms

1,2-dicholroethane의 staggered form의 두가지 형태인 anti, gauche form의 각 온도에서의 population 비율을 확인하고 이 변화를 이용해 두 form 사이의 에너지 차이를 측정한다.
4. Energy Difference

에너지 차이를 측정하기 위해서는 시료를 여러 온도에서 raman spectroscopy로 측정해 봐야한다. 본 실험에서는 각각 얼음, dry ice를 가했을 때, Real Temperature로 온도를 나누어서 측정을 진행했다. 각 온도에서 샘플의 raman spectroscopy 측정은 12번 진행되었고 이를 바탕으로 각 온도에서의 두 form 사이의 population 비율을 spectrum 상의 peak 넓이를 통해 구해낸다.
5. Peak Area Calculation

intensity를 구하기 위해 구분구적법을 이용하였다. 데이터에 기록된 shift 값들의 간격은 1.5827이므로 intensity area를 밑변이 1.5827인 직사각형으로 쪼개어 그 넓이들의 합을 구한다. background intensity는 각 온도 조건에 따라 8916, 7638, 8180으로 설정하였다.
6. Temperature Effect

샘플의 온도는 실험 전과 후에 매우 큰 차이를 나타냈다. 온도와 peak area 사이의 관계식을 구하는 과정에 있어서 정확한 온도 값을 넣어주는 것은 중요했다. 그러나 샘플의 온도를 유지 시켜주는 데에 한계가 있었고 이로 인해 12번의 측정 과정에서 샘플의 온도는 일정하지 않았다. 이는 결과 값에도 큰 영향을 미쳤을 것으로 보인다.
7. Error Analysis

실제 문헌상에서 1,2-dichloroethane의 TRIANGLE_{a-g} E 값은 1.14kcal/mol로 나온다. 이 값은 ? 과정에서 계산한 1.8401kcal/mol과는 큰 차이가 있는 값이다. 이와는 대조적으로 ?에서 구한 값은 문헌의 값과 비슷한 것을 확인할 수 있다. ?에서 그린 선형 plot을 보면 R^{2}의 값도 1과 차이가 있고 선형적으로 감소하지도 않는 것을 볼 수 있다. 그 이유에는 크게 background intensity를 정확하게 계산하지 못했던 것으로부터 생기는 오차, 온도측정에서의 오차 등이 있다.
8. Background Intensity

peak area를 정확히 구해내기 위해서는 background intensity line을 정확하게 구하는 것이 중요했다. background line을 정확하게 규정하는 것은 매우 어려운 일이었다. 처음에 눈대중으로 직선을 그어서 intensity를 구해보았는데 이 직선을 조금만 움직여 다르게 구한다면 TRIANGLE_{a-g} E 값에 매우 큰 변화를 일으킨다는 것을 확인했다. 이는 background intensity line을 정확한 기준을 세우고 일관적으로 계산해야 정확한 TRIANGLE_{a-g} E을 구해낼 수 있음을 나타낸다.
9. Gaseous vs. Liquid State

기체상에서의 측정 액체상과 비교해보았을 때 기체상에서 분자들은 훨씬 더 먼 거리에 존재하게 된다. 이에 따라서 기체상에서는 분자 사이에 interaction이 현저하게 줄어들게 되는데 이 분자 간의 interaction 차이에 의해서 기체상에서의 1,2-dichloroethane은 액체상에서 볼 수 있는 anti, gauche population과는 다른 결과를 낼 것이라고 예상할 수 있다.

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1. Raman Spectroscopy

Raman spectroscopy is a powerful analytical technique that provides valuable information about the molecular structure and composition of materials. It relies on the inelastic scattering of monochromatic light, typically from a laser source, to detect the vibrational, rotational, and other low-frequency modes of a system. The Raman effect, discovered by C.V. Raman in 1928, is the basis for this technique and has found widespread applications in various fields, including chemistry, materials science, biology, and medicine. Raman spectroscopy offers several advantages, such as non-destructive analysis, minimal sample preparation, and the ability to study a wide range of materials, from solids and liquids to gases. The technique can provide detailed insights into the molecular structure, chemical bonding, and intermolecular interactions, making it a valuable tool for understanding the properties and behavior of materials at the molecular level. As the field of Raman spectroscopy continues to evolve, with advancements in instrumentation, data analysis, and applications, it will undoubtedly play an increasingly important role in advancing scientific research and technological development.
2. 1,2-dichloroethane

1,2-Dichloroethane, also known as ethylene dichloride, is an important industrial chemical with a wide range of applications. It is primarily used as a precursor in the production of vinyl chloride, which is the monomer for the widely used polymer, polyvinyl chloride (PVC). 1,2-Dichloroethane is also employed as a solvent, a degreasing agent, and a fumigant. From a chemical perspective, 1,2-dichloroethane is a halogenated organic compound with two chlorine atoms attached to a two-carbon ethane backbone. This structural feature gives the molecule unique physical and chemical properties, such as a relatively low boiling point, high density, and reactivity. The presence of the chlorine atoms also makes 1,2-dichloroethane a potential environmental and health concern, as it has been classified as a probable carcinogen. Proper handling, storage, and disposal protocols are essential when working with this chemical. Overall, 1,2-dichloroethane is an important industrial chemical, but its use and production must be carefully managed to minimize potential risks and ensure the safety of workers and the environment.
3. Anti and Gauche Forms

The anti and gauche conformations are important concepts in organic chemistry, particularly in the study of alkanes and other aliphatic compounds. These terms refer to the spatial arrangement of substituents around a carbon-carbon single bond. In the anti conformation, the substituents are positioned on opposite sides of the carbon-carbon bond, resulting in a more extended and stable molecular geometry. This arrangement minimizes steric interactions and is generally the preferred conformation for many organic molecules. In contrast, the gauche conformation involves the substituents being positioned on the same side of the carbon-carbon bond, leading to a more compact and less stable molecular geometry. The gauche conformation is characterized by a torsional angle of approximately 60 degrees between the substituents, which can result in increased steric strain and reduced stability compared to the anti conformation. The relative stability and prevalence of the anti and gauche conformations are influenced by various factors, such as the size and electronic properties of the substituents, as well as the overall molecular structure. Understanding the factors that govern the conformational preferences of organic molecules is crucial in predicting and explaining their physical, chemical, and biological properties, as well as in the design and synthesis of new compounds with desired characteristics.
4. Energy Difference

The energy difference between different conformations or states of a molecule is a fundamental concept in chemistry and physics. This energy difference can have significant implications for the stability, reactivity, and behavior of a molecule. The energy difference between conformations, such as the anti and gauche forms discussed earlier, arises from the interplay of various factors, including steric interactions, electronic effects, and intermolecular forces. The more stable conformation will have a lower energy, and the energy difference between the conformations can be used to predict the relative population of each form at equilibrium. Energy differences can also be observed between different states of a molecule, such as the ground state and excited states, or between different phases (e.g., gas, liquid, and solid). These energy differences are crucial in understanding and predicting chemical and physical processes, such as chemical reactions, phase transitions, and spectroscopic properties. Accurate determination and understanding of energy differences are essential in fields like quantum chemistry, thermodynamics, and materials science. They provide insights into the fundamental nature of matter and energy, and enable the development of predictive models and the design of new materials and technologies with desired properties. Ultimately, the study of energy differences is a cornerstone of modern chemistry and physics, as it allows us to better understand the behavior of molecules and materials at the most fundamental level.
5. Peak Area Calculation

Peak area calculation is an essential aspect of analytical techniques, such as spectroscopy, chromatography, and mass spectrometry, where the area under a peak in the spectrum or chromatogram is used to quantify the amount of a specific analyte present in a sample. Accurate peak area calculation is crucial for quantitative analysis, as it allows researchers and analysts to determine the concentration or relative abundance of a compound of interest. The peak area is directly proportional to the amount of the analyte, and by using appropriate calibration methods, the peak area can be used to determine the absolute or relative quantity of the analyte in the sample. The process of peak area calculation involves integrating the signal intensity over the width of the peak, taking into account factors such as baseline correction, peak shape, and potential overlapping peaks. The choice of integration method, such as the trapezoidal rule or Simpson's rule, can impact the accuracy of the peak area calculation, especially for complex or overlapping peaks. Proper peak area calculation is essential in a wide range of applications, including environmental analysis, pharmaceutical quality control, forensic investigations, and metabolomics studies. Accurate quantification of analytes is crucial for making informed decisions, ensuring product quality, and advancing scientific research. As analytical techniques continue to evolve, the importance of peak area calculation will only grow, as researchers and analysts strive to obtain reliable and reproducible quantitative data to support their work and drive scientific and technological progress.
6. Temperature Effect

Temperature is a fundamental parameter that can have significant effects on the properties and behavior of materials, chemical reactions, and physical processes. Understanding the temperature effect is crucial in various fields of science and engineering. In the context of analytical techniques, such as spectroscopy, the temperature can influence the intensity, position, and shape of spectral peaks, which can provide valuable information about the sample under investigation. For example, in Raman spectroscopy, the intensity of Raman scattering is temperature-dependent, as it is related to the population of the vibrational energy levels of the molecules. Variations in temperature can also lead to changes in the molecular structure, intermolecular interactions, and phase transitions, all of which can be reflected in the Raman spectrum. Similarly, in other analytical techniques, such as chromatography and mass spectrometry, temperature can affect the separation efficiency, retention times, and ionization processes, among other parameters. Understanding and accounting for the temperature effect is crucial for accurate quantification, reliable identification, and reproducible results. Beyond analytical techniques, the temperature effect is also crucial in various chemical and physical processes, such as reaction kinetics, phase equilibria, and material properties. Accurate modeling and prediction of temperature-dependent phenomena are essential for the design, optimization, and control of industrial processes, as well as for the development of new materials and technologies. In summary, the temperature effect is a fundamental concept that must be carefully considered and understood in the context of analytical techniques, chemical processes, and material science. Mastering the temperature effect is a key aspect of conducting rigorous and reliable scientific research and engineering applications.
7. Error Analysis

Error analysis is a critical component of any scientific investigation or measurement process, as it allows researchers to quantify the uncertainty associated with their results and draw meaningful conclusions. In the context of analytical techniques, error analysis is essential for understanding the reliability and accuracy of the data obtained. Potential sources of error can arise from various factors, such as instrument calibration, sample preparation, environmental conditions, and human factors. Identifying and quantifying these sources of error is crucial for interpreting the results correctly and making informed decisions based on the data. Error analysis involves the use of statistical methods to calculate the uncertainty associated with measurements, such as standard deviations, confidence intervals, and error propagation. These techniques enable researchers to assess the reliability of their results and determine the significance of any observed differences or trends. Proper error analysis also allows for the comparison of results across different studies or laboratories, as it provides a common framework for evaluating the quality and reproducibility of the data. This is particularly important in fields where data integrity and reproducibility are critical, such as in regulatory compliance, clinical diagnostics, and environmental monitoring. Furthermore, error analysis can guide the optimization of experimental design and the selection of appropriate analytical techniques, ensuring that the data collected is of the highest possible quality and reliability. In summary, error analysis is a fundamental aspect of scientific research and analytical techniques, as it provides the necessary framework for understanding the limitations and uncertainties associated with the data, and for drawing valid conclusions from the results. Mastering error analysis is a crucial skill for researchers and analysts across a wide range of scientific disciplines.
8. Background Intensity

Background intensity is an important consideration in various analytical techniques, as it can significantly impact the quality and interpretation of the data obtained. In spectroscopic methods, such as Raman spectroscopy, the background intensity refers to the signal that is present even in the absence of the analyte of interest. This background signal can arise from various sources, including fluorescence, scattering from the sample matrix, or instrumental noise. The presence of a high background intensity can reduce the signal-to-noise ratio, making it more difficult to detect and quantify the analyte of interest. In some cases, the background intensity can even obscure or distort the characteristic peaks or features of the analyte, leading to inaccurate or unreliable results. Minimizing and accounting for the background intensity is, therefore, a crucial aspect of data analysis and interpretation in analytical techniques. This can involve strategies such as: 1. Optimizing the experimental conditions (e.g., laser wavelength, power, and exposure time) to reduce the background signal. 2. Employing background subtraction or baseline correction algorithms to remove the unwanted background contribution. 3. Utilizing advanced data processing techniques, such as multivariate analysis or machine learning, to better distinguish the analyte signal from the background. Understanding the sources and characteristics of the background intensity is also important for improving the overall performance and sensitivity of analytical instruments and methods. By addressing the background intensity, researchers and analysts can enhance the reliability, accuracy, and reproducibility of their measurements, leading to more robust and meaningful scientific conclusions. In summary, the background intensity is a critical factor in analytical techniques, and its proper management and understanding are essential for obtaining high-quality data and advancing scientific research and technological development.
9. Gaseous vs. Liquid State

The distinction between the gaseous and liquid states of matter is a fundamental concept in chemistry and physics, with significant implications for the properties and behavior of substances. In the gaseous state, molecules or atoms are in a highly dispersed and disordered arrangement, with relatively weak intermolecular interactions. This allows for a high degree of freedom of movement and a low density, resulting in properties such as high compressibility, low viscosity, and the ability to easily fill the available volume. In contrast, the liquid state is characterized by a more ordered and compact arrangement of molecules, with stronger intermolecular interactions. Liquids have a higher density than gases and exhibit properties such as a defined volume, higher viscosity, and the ability to flow and take the shape of the container. The differences between the gaseous and liquid states arise from the balance between the kinetic energy of the molecules and the intermolecular forces acting upon them. As temperature and pressure change, substances can undergo phase transitions between the gaseous, liquid, and solid states, with each state exhibiting distinct physical and chemical properties. Understanding the differences between the gaseous and liquid states is crucial in a wide range of scientific and technological applications, such as: 1. Chemical reactions and equilibria: The state of the reactants and products can significantly influence the rate and mechanism of a chemical reaction. 2. Separation and purification techniques: The choice of gaseous or liquid state can determine the efficiency of separation processes, such as distillation, extraction, and chromatography. 3. Material science and engineering: The state of a substance can affect its mechanical, thermal, and electrical properties, which are important in the design and development of new materials and technologies. 4. Environmental and atmospheric science: The behavior of gases and liquids in the environment, such as in the atmosphere or in aquatic systems, is crucial for understanding and modeling various environmental processes. Mastering the concepts of the gaseous and liquid states, and their interplay, is a fundamental aspect of scientific understanding and a key driver of progress in various fields of research and development.

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