Modeling of CO2 Gas Excitation Under CO2 Laser Irradiation

Author(s):  
Lan Jiang ◽  
Hai-Lung Tsai

Lasers especially multiple laser beams demonstrate unique advantages as energy sources in diamond synthesis. However, the fundamental mechanisms involved in the laser-assisted processes are not Well understood. In a reported amazingly-fast multiple laser coating technique, CO2 gas is claimed as the sole precursor or secondary precursor, which remains poorly understood and unverified. The absorption coefficient changes under the irradiation of the multiple lasers are one of the keys to resolve the mysteries of multiple laser beam coating processes. This study investigates the optical absorption in CO2 gas at the CO2 laser wavelength. This resonance absorption process is modeled as an inverse process of the lasing transitions of CO2 lasers. The well-established CO2 vibrational-rotational energy structures are used as the basis for the calculations with the Boltzmann distribution for equilibrium states and the three-temperature model for non-equilibrium states. Based on the population distribution, our predictions of CO2 absorption coefficient changes as the function of temperature are in agreement with the published data.

2009 ◽  
Vol 97 (1) ◽  
pp. 199-206 ◽  
Author(s):  
L. Jiang ◽  
L. Li ◽  
H.-L. Tsai

2020 ◽  
pp. 139-143

Natural dyes were followed and prepared from a pomegranate, purple carrot, and eggplant peel. The absorbance spectra was measured in the wavelength range 300-800 nm. The linear properties measurements of the prepared natural dye freestanding films were determined include absorption coefficient (α0), extinction coefficient (κ), and linear refraction index (n). The nonlinear refractive index n2 and nonlinear absorption coefficient β2 of the natural dyes in the water solution were measured by the optical z-scan technique under a pumped solid state laser at a laser wavelength of 532 nm. The results indicated that the pomegranate dye can be promising candidates for optical limiting applications with significantly low optical limiting of 3.5 mW.


1989 ◽  
Vol 43 (1) ◽  
pp. 148-153 ◽  
Author(s):  
Dane Bićanić ◽  
Siegfried Krüger ◽  
Paul Torfs ◽  
Bruno Bein ◽  
Frans Harren

An experimental setup for performance of reverse mirage spectroscopy at CO2 laser wavelengths on liquid samples having high values of absorption coefficients is described. One and the same liquid is used as both the absorbing and deflecting medium. The Rosencwaig-Gersho theory has been applied, and the choice of experimental conditions that would enable determination of absorption coefficient β from the magnitude of photothermal signals measured at two different probe beam distances (probing locations) is discussed. The usefulness of this technique (essentially not inhibited by the requirements imposed on the sample's thickness) is tested on methanol having absorption coefficients β close to 300 cm−1 in the wavelength region covered by CO2 laser emission.


1951 ◽  
Vol 18 (1) ◽  
pp. 53-58
Author(s):  
S. S. Penner

Abstract An approximate method for estimating radiant-heat transfer from gaseous emitters has been developed. An average absorption coefficient is used for an effective width of an entire vibration-rotation band. The procedure for determining an average absorption coefficient in terms of integrated absorption can be justified, approximately, for very large total pressures where the spectral half-width is no longer small compared with the rotational spacing. Because of this limitation, it is to be expected that the procedure proposed here will be particularly useful only in estimating gaseous emissivities for emitters in high-pressure combustion chambers. Nevertheless, it appears that the simplified procedure yields reasonable results even at relatively low total pressures. Thus a comparison of calculated and observed emissivities for CO at atmospheric pressure shows satisfactory agreement, especially at large optical densities. Representative emissivity calculations over a wide temperature range are described. Emissivity calculations on CO, NO, HF, HCl, HBr, and HI can be carried out very rapidly by the use of recently published data on these gases.


1985 ◽  
Vol 17 (2) ◽  
pp. 96-98 ◽  
Author(s):  
D. Ignjatijevic ◽  
P. Vujkovic Cvijin ◽  
M. Sreckovic ◽  
I. Pippi

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 4782-4782
Author(s):  
Jyotsna Mehta ◽  
Adeline Abbe ◽  
Peter C Trask ◽  
Frank Neumann ◽  
Alaa Hamed

Abstract Abstract 4782 Background: Hodgkin lymphoma represents 11.7% of all types of lymphoma diagnosed in 2011. (Leukemia and Lymphoma Society) In 2012, an estimated 9,060 of new HL cases and 1,190 deaths will occur in North America and mostly in either young adults between 15 and 30 years of age, or after the age of 45. (American Cancer Society) The five-year relative survival rate for all patients with HL is 86.3% from 2001 to 2007 and 92.8% for patients less than 45 years at diagnosis. (SEER Review) Initial treatment of HL depends on the stage of the disease at diagnosis. Chemotherapy with or without radiation therapy is the most common treatment approach for HL patients. Stem cell transplantation and chemotherapy are the treatment options for patients with relapse disease. There is lack of published data on the distribution of patients across lines of therapy as well as percentage of relapsed and refractory patients. Understanding the distribution of patients across lines of therapy is critical to identify the unmet need and to help tailor future therapies. Methods: Epidemiological data was obtained for US and EU using the 'epic oncology' 2012 database (Epiphany Partners Inc.). The database includes line of therapy estimations using an advanced patient flow model combining survival by subset and course of treatment, response rates and outcomes, and treatment data from US and EU cancer registries coupled with primary research with a representative sample of physicians and secondary therapeutic reviews. We analyzed projection estimates up to 2020 across US and EU5 countries by line of therapy with specific attention to relapsed/refractory patients. These projection estimates are based on the current treatment options and does not account for introduction of future therapies. Refractory patients are defined as those who do not respond (do not go into remission) following therapy. Relapsed Patients are defined as those who have responded to therapy (enter remission) but re-enter the treatment population at a later stage due to progression of their cancer, recurrence of diagnostic markers, or symptomatology. Results: Projection estimates from 2010 to 2020 by line of therapy varied by country. Among EU countries, the highest number of treated HL patients was in France, followed by Italy and Spain. By 2020, the percentage of patients that are either relapsed or refractory to first, second and third line of therapy will increase by about 25% in US and by about 15% in EU. Regional variation observed across Europe are as follows: an increase by 38% in Spain, 25% in France, 12% in UK and 6% in Italy, while Germany will show a decline of 2%, this is due to a continuous decline in incidence rates since the early 1990s. Drug treated Hodgkin lymphoma population by line of therapy*: Conclusions: Due to the highly chemosensitive nature of the malignancy, only about 25% of Hodgkin lymphoma patients progress to a second line therapy and 30% of those move into third line. Smaller sample sizes, variation in growth rate among US and EU countries, and a bimodal incidence curve could cause differences in projection trends. The creation of a Hodgkin's disease based registry can help in validating emerging trends in therapy through providing up to date global projection estimates across line of therapy. Our results provide a global understanding of the HL patient population distribution across lines of therapy and are critical to identify the unmet need and guide future therapies in HL patients. Disclosures: Mehta: Sanofi: Employment. Abbe:Sanofi: Employment, Equity Ownership. Trask:Sanofi: Employment. Neumann:Sanofi-aventis: Employment. Hamed:Sanofi: Employment.


1979 ◽  
Vol 57 (11) ◽  
pp. 1896-1897 ◽  
Author(s):  
A. M. Robinson

The line-center absorption coefficient of CO2, has been measured as a function of temperature from 295 to 650 K for the P(26)–P(32) laser transitions.


2018 ◽  
Vol 9 (2) ◽  
pp. 42
Author(s):  
S Setiadi ◽  
Dijan Supramono ◽  
Nur Istiqomah

Efforts to improve the performance of CO2 absorption using bubbling columns and liquid jet flow have consistently been developed. The advantage of the present column is the presence of gas entrainment by suction of nozzle and the gas dispersed throughout the bulk of liquid by the formation of bubble clouds. The selection of liquid jet flow configuration used parameters of nozzle position and liquid jet inclination. The configurations have been examined by hydrodynamic test by measuring the ratio of volumetric rate of gas to that of liquid exiting nozzle (QG/QL) and gas holdup. Absorption test to the best configuration used NaOH solution with flowrate of 5 litres/min at atmospheric pressure and CO2 gas feed of 96.6%. The results showed that the configurations of liquid jet flow gave significant effect on hydrodynamics and that the best configurations had gas hold-up in the range of 0.55-0.6 and QG/QL 1.3-1.8. Absorption tests showed that CO2 concentration can be reduced into 0.01%-0.07% in less than five minutes and the absorption should proceed with the chemical reaction up to 10 minutes with no indication of CO2 desorption. The bubbles were generated in the column predominantly in the diameter range of 0.00097-0.00184 mm.Keywords: Configurations of liquid jet, bubble column, gas entrainment, CO2 gas absorption AbstrakUpaya meningkatkan kinerja absorpsi gas CO2 yang memanfaatkan kolom gelembung dan liquid jet flow telah banyak dilakukan. Keunggulan kolom gelembung dalam riset ini adalah kolom menyebabkan gas entrainment (pengisapan gas) dan dispersi gas ke dalam cairan yang membentuk awan gelembung. Pemilihan konfigurasi liquid jet flow terbaik berdasarkan posisi nosel dan arah sudut tembakannya dan dengan mengukur rasio laju volumetrik aliran gas entrainment terhadap laju volumetrik aliran cairan (QG/QL) serta gas hold-up untuk setiap konfigurasi. Konfigurasi terbaik digunakan untuk menentukan kinerja kolom gelembung untuk mendapatkan kinerja kemampuan absorpsi yang setinggi-tingginya. Uji absorpsi dilakukan terhadap konfigurasi terbaik dengan menggunakan absorben larutan NaOH dengan laju alir 5 L/min pada tekanan atmosferik dan umpan gas CO2 dengan kadar 96,6%. Hasil penelitian menunjukkan bahwa konfigurasi memberikan pengaruh cukup signifikan dan bahwa konfigurasi terbaik memberikan gas hold-up kisaran 0,55-0,65 dan rasio QG/QL bernilai 1,3-1,8. Uji absorpsi menunjukkan berkurangnya kadar CO2 menjadi 0,01% hingga 0,07% setelah absorpsi kurang dari 5 menit dan tetap tidak berubah sampai 10 menit. Hal ini menandakan bahwa absorpsi terjadi secara kimiawi antara gas CO2 dan NaOH and tidak terjadi desorpsi walaupun kolom gelembung tetap resirkulasi. Populasi gelembung menunjukkan distribusi ukuran gelembung lebih dominan pada rentang diameter antara 0,00097-0,00184 mm.Kata Kunci: Konfigurasi liquid jet, kolom gelembung, gas entrainment, absorpsi gas CO2


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