Abstract This paper presents aerosol light absorption measurements using a seven channel Aethalometer (AE-42), recorded during September 2011–November 2012 over a tropical semi-arid site in Kadapa, India. The annual average black carbon... more
Abstract This paper presents aerosol light absorption measurements using a seven channel Aethalometer (AE-42), recorded during September 2011–November 2012 over a tropical semi-arid site in Kadapa, India. The annual average black carbon (BC) mass concentration ([BC]) during the studied period was 2.20 ± 0.78 μg m − 3 which is in agreement when compared to other sites of similar environment. Strong seasonal variation was observed with high values during winter (2.87 ± 0.81 μg m − 3 ) and low in monsoon (1.30 ± 0.31 μg m − 3 ) season, which could be attributed to regional synoptic meteorology and long range transport. The two peaks in diurnal variations of [BC] were observed during morning between 06:00 and 08:00 h local time (LT) and in the evening around 19:00–21:00 h LT, with a minimum peak in the afternoon (~ 16:00 h LT) which is strongly correlated with the boundary layer dynamics, local and regional sources, and associated meteorology. The relationships between measured [BC] and the corresponding meteorological parameters for the studied region were also analysed. The estimated monthly mean spectral absorption coefficient values range from 0.56 to 1.15 with an average of 0.90, which suggests high BC/OC ratio and possible source of emission of aerosols is fossil fuel burning. Trajectory cluster analysis showed significant impact of long range transport of BC aerosols towards the observational site during the period of study.
Research Interests:
A simple empirical relationship has been established for the estimation of lattice energies of ionic crystals directly from the electronegativity values of Martynov and Bastsanov. These values are used to estimate mean sound velocities in... more
A simple empirical relationship has been established for the estimation of lattice energies of ionic crystals directly from the electronegativity values of Martynov and Bastsanov. These values are used to estimate mean sound velocities in Kudriavtsev's theory. Excellent agreement is observed between the computed and literature values of lattice energy and mean sound velocity. the merits of the present approach are discussed
Research Interests:
The experimental potential energy curves for the electronic ground states of molecules like CO+, CH and CH+ observed in comets are constructed by using the Rydberg–Klein–Rees method as modified by Vanderslice et al. The ground state... more
The experimental potential energy curves for the electronic ground states of molecules like CO+, CH and CH+ observed in comets are constructed by using the Rydberg–Klein–Rees method as modified by Vanderslice et al. The ground state dissociation energies are determined by curve fitting technique using the five parameter Hulburt–Hirschfelder (H–H) function. The estimated dissociation energies are 8.33±0.19, 3.48±0.903 and 3.89±0.102eV
Research Interests:
Research Interests:
A total eclipse occurred on july the 22th of 2009 over India, starting from Bombay and crossing the country toward the east. During this event, an EZ Aerosol LIDAR™ has been monitoring at the National Physics Lab, making high resolution... more
A total eclipse occurred on july the 22th of 2009 over India, starting from Bombay and crossing the country toward the east. During this event, an EZ Aerosol LIDAR™ has been monitoring at the National Physics Lab, making high resolution and continuous observations of the atmosphere at 355nm. Polarisation measurements were also taken. The eclipse in Indian continent started about 4;30 early in the morning . In Delhi It was between 6:00 AM to 7 :00AM on 22-7-09 . In this time interval the signature of wave pattern is observed. These lidar results show some experimental evidence which support the hypothesis that the movement of moon's shadow sweeping the ozone layer at supersonic speed during a solar eclipse , creates gravity waves in the atmosphere.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
To better understand the sources as well as characterization of regional aerosols at a rural semi-arid region Kadapa (India), size-resolved composition of atmospheric particulate matter (PM) mass concentrations was sampled and analysed.... more
To better understand the sources as well as characterization of regional aerosols at a rural semi-arid region Kadapa (India), size-resolved composition of atmospheric particulate matter (PM) mass concentrations was sampled and analysed. This was carried out by using the Anderson low-pressure impactor for a period of 2 years during March 2013-February 2015. Also, the variations of organic carbon (OC), elemental carbon (EC) and water-soluble inorganic ion components (WSICs) present in total suspended particulate matter (TSPM) were studied over the measurement site. From the statistical analysis, the PM mass concentration showed a higher abundance of coarse mode particles than the fine mode during pre-monsoon season. In contrast, fine mode particles in the PM concentration showed dominance over coarse mode particle contribution during the winter. During the post-monsoon season, the percentage contributions of coarse and fine fractions were equal, whereas during the monsoon, coarse mode fraction was approximately 26 % higher than the fine mode. This distinct feature in the case of fine mode particles during the studied period is mainly attributed to large-scale anthropogenic activities and regional prevailing meteorological conditions. Further, the potential sources of PM have been identified qualitatively by using the ratios of certain ions. A high sulphate (SO4) concentration at the measurement site was observed during the studied period which is caused by the nearby/surrounding mining activity. Carbon fractions (OC and EC) were also analysed from the TSPM, and the results indicated (OC/EC ratio of ~4.2) the formation of a secondary organic aerosol. At last, the cluster backward trajectory analyses were also performed at Kadapa for different seasons to reveal the origin of sources from long-range transport during the study period.
Research Interests:
A new family of three optical glasses of the following chemical composition with 1 mol% of Nd3+ were prepared to examine the effects of alkali fluorides in unmixed form: 40(NaPO3)6+10BaF2+9ZnF2+20B2O3+20RF+1NdF3, where RF=LiF, NaF and KF.... more
A new family of three optical glasses of the following chemical composition with 1 mol% of Nd3+ were prepared to examine the effects of alkali fluorides in unmixed form: 40(NaPO3)6+10BaF2+9ZnF2+20B2O3+20RF+1NdF3, where RF=LiF, NaF and KF. On the basis of the measured values of densities and refractive indices, the dielectric constant, reflection losses, molar refraction, Nd3+ ion concentration in glasses and
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
... References [1] WA Harrison, Electronic Structure and the Properties of Solids; The Physics of the Chemical Bond, WH Freeman, San Francisco, 1980. [2] RR Reddy, ASR Reddy and S.Anjaneyulu, J. Mol. Struct. ... [18] KVSiva Kumar and E.... more
... References [1] WA Harrison, Electronic Structure and the Properties of Solids; The Physics of the Chemical Bond, WH Freeman, San Francisco, 1980. [2] RR Reddy, ASR Reddy and S.Anjaneyulu, J. Mol. Struct. ... [18] KVSiva Kumar and E. Rajagopal, Acoust. Lett., 7 (1983) 87. ...
Research Interests:
ABSTRACT In this report, we attempt to quantify direct aerosol radiative forcing by considering the diurnal variation of aerosols over central Himalayan region. The measured day time aerosol optical depth (AOD) values are higher by a... more
ABSTRACT In this report, we attempt to quantify direct aerosol radiative forcing by considering the diurnal variation of aerosols over central Himalayan region. The measured day time aerosol optical depth (AOD) values are higher by a small magnitude≤15% during forenoon and reached as high as 90% by late afternoon when compare to night time AOD. The above observation gives clue about transport of regional polluted aerosols to the observational site. Our results show, 10 (16) % increment in atmospheric radiative forcing due to diurnal variation of aerosols instead of average aerosols during winter (post-monsoon) season.
The experimental potential energy curves for the different electronic states of molecules like CN, CO and CS observed in comets are constructed by using the Rydberg-Klein-Rees method as modified by Vanderslice et al. The ground state... more
The experimental potential energy curves for the different electronic states of molecules like CN, CO and CS observed in comets are constructed by using the Rydberg-Klein-Rees method as modified by Vanderslice et al. The ground state dissociation energies are determined by curve fitting technique using the five parameter Hulburt-Hirschfelder (H-H)function. The estimated dissociation energies are 7.63 0.187, 10.95 0.224 and
Research Interests:
A micro pulse lidar (MPL) has been indigenously designed and developed at the National Physical Laboratory, New Delhi using a 532 nm, 500 pico second pulsed laser having average power of 50mW (at 7.5 KHz PRR). Photon counting technique... more
A micro pulse lidar (MPL) has been indigenously designed and developed at the National Physical Laboratory, New Delhi using a 532 nm, 500 pico second pulsed laser having average power of 50mW (at 7.5 KHz PRR). Photon counting technique has been incorporated using the conventional optics, multichannel scaler (Stanford Research Systems SR430) and high sensitive photomultiplier tube. The sensitivity, range
Research Interests:
The ozone-mixing ratio in ambient air is being measured for every 15 min at Anantapur, a semi-arid zone since April 2001 and analysed. The results show diurnal, day-to-day and seasonal variability. A typical diurnal variation shows an... more
The ozone-mixing ratio in ambient air is being measured for every 15 min at Anantapur, a semi-arid zone since April 2001 and analysed. The results show diurnal, day-to-day and seasonal variability. A typical diurnal variation shows an increase during the day, reaching maximum around local noon. However, the diurnal minimum is reached about an hour after sunrise but not during night. The other important feature observed is that the magnitude of the diurnal variation as well as the absolute concentrations of ozone are much higher in winter and summer than in autumn. While the average ozone during noon hours in autumn months is about 25 ppbv, it becomes as high as 50 ppbv during winter and summer months.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
A new family of three optical glasses of the following chemical composition with 1 mol% of Nd3+ were prepared to examine the effects of alkali fluorides in unmixed form: 40(NaPO3)6+10BaF2+9ZnF2+20B2O3+20RF+1NdF3, where RF=LiF, NaF and KF.... more
A new family of three optical glasses of the following chemical composition with 1 mol% of Nd3+ were prepared to examine the effects of alkali fluorides in unmixed form: 40(NaPO3)6+10BaF2+9ZnF2+20B2O3+20RF+1NdF3, where RF=LiF, NaF and KF. On the basis of the measured values of densities and refractive indices, the dielectric constant, reflection losses, molar refraction, Nd3+ ion concentration in glasses and
Research Interests:
A new method for calculating the optical basicity, electronic polarizability and oxygen electronegativity of oxides and oxysalts has been evaluated based on the concept of average electronegativity given by Asokamani and Manjula. The... more
A new method for calculating the optical basicity, electronic polarizability and oxygen electronegativity of oxides and oxysalts has been evaluated based on the concept of average electronegativity given by Asokamani and Manjula. The estimated parameters ...
Research Interests:
... Technol. 30 (1995), p. 263. View Record in Scopus | Cited By in Scopus (7). 13. RR Reddy, M. Ravi Kumar and TVR Rao. Infrared Phys. 34 (1993), p. 99. ... 15. JA Duffy. Phys. C 13 (1980), p. 2979. 16. VP Gupla and NM Ravindra. Phys.... more
... Technol. 30 (1995), p. 263. View Record in Scopus | Cited By in Scopus (7). 13. RR Reddy, M. Ravi Kumar and TVR Rao. Infrared Phys. 34 (1993), p. 99. ... 15. JA Duffy. Phys. C 13 (1980), p. 2979. 16. VP Gupla and NM Ravindra. Phys. Status Solidi (b) 100 (1980), p. 715. 17. ...
Research Interests:
A new family of three neodymium doped alkali fluoroborophosphate glasses with mixed alkali fluorides as network modifiers have been prepared to study their physical and absorption properties at room temperature. The refractive indices (at... more
A new family of three neodymium doped alkali fluoroborophosphate glasses with mixed alkali fluorides as network modifiers have been prepared to study their physical and absorption properties at room temperature. The refractive indices (at 589.3 nm) and densities of these glasses ...
Research Interests:
... relations. RR Reddy Corresponding Author Contact Information , E-mail The Corresponding Author , a , Y. Nazeer Ahammed a , K. Rama Gopal a , P. Abdul Azeem a , B. Sasikala Devi a , TVR Rao a and SH Behere b. ... polarizability. Kumar... more
... relations. RR Reddy Corresponding Author Contact Information , E-mail The Corresponding Author , a , Y. Nazeer Ahammed a , K. Rama Gopal a , P. Abdul Azeem a , B. Sasikala Devi a , TVR Rao a and SH Behere b. ... polarizability. Kumar et al. ...
Research Interests:
Correlations between the energy gap, optical electronegativity and bulk modulus are given for compound and ternary chalcopyrite semiconductors. Bulk modulus and electronic polarizability values have been evaluated from the optical... more
Correlations between the energy gap, optical electronegativity and bulk modulus are given for compound and ternary chalcopyrite semiconductors. Bulk modulus and electronic polarizability values have been evaluated from the optical electronegativity. The estimated ...
Research Interests:
In recent years, high-resolution photoelectron spectroscopy and ab initio calculations have considerably revised and enlarged the understanding of the electronic structure of the NO and NO + molecules. The experimental potential energy... more
In recent years, high-resolution photoelectron spectroscopy and ab initio calculations have considerably revised and enlarged the understanding of the electronic structure of the NO and NO + molecules. The experimental potential energy curves for the different electronic states of ...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
ABSTRACT
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Optical susceptibility, electronic polarizability and magnetic susceptibility values have been evaluated from optical electronegativities. The validity of the proposed empirical relations has been tested in the case of IIVI, IIIV group... more
Optical susceptibility, electronic polarizability and magnetic susceptibility values have been evaluated from optical electronegativities. The validity of the proposed empirical relations has been tested in the case of IIVI, IIIV group semiconductors and alkali halides. The ...