TY  - JOUR
A1  - Ojha, Animesh K.
A1  - Forster, Stefan
A1  - Kumar, Sumeet
A1  - Vats, Siddharth
A1  - Negi, Segeeta
A1  - Fischer, Ingo
T1  - Synthesis of well-dispersed silver nanorods of different aspect ratios and their antimicrobial properties against gram positive and negative bacterial strains
JF  - Journal of Nanobiotechnology
N2  - In the present contribution, we describe the synthesis of highly dispersed silver nanorods (NRs) of different aspect ratios using a chemical route. The shape and size of the synthesized NRs were characterized by Transmission Electron Microscopy (TEM) and UV-visible spectroscopy. Longitudinal and transverse absorptions bands confirm the rod type structure. The experimentally recorded UV-visible spectra of NRs solutions were fitted by using an expression of the extinction coefficient for rod like nano structures under the dipole approximation. Simulated and experimentally observed UV-visible spectra were compared to determine the aspect ratios (R) of NRs. The average values of R for NR1, NR2 and NR3 solutions are estimated to be 3.0 +/- 0.1, 1.8 +/- 0.1 and 1.2 +/- 0.1, respectively. These values are in good agreement with those obtained by TEM micrographs. The silver NRs of known aspect ratios are used to study antimicrobial activities against B. subtilis (gram positive) and E. coli (gram negative) microbes. We observed that the NRs of intermediate aspect ratio (R = 1.8) have greater antimicrobial effect against both, B. subtilis (gram positive) and E. coli (gram negative). The NRs of aspect ratio, R = 3.0 has better antimicrobial activities against gram positive than on the gram negative.
KW  - silver
KW  - nano rods
KW  - TEM
KW  - antimicrobial activities
KW  - nanowire formation
KW  - gold nanoparticles
KW  - Raman-scattering
KW  - nanostructures
KW  - particles
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-122837
SN  - 1477-3155
VL  - 11
IS  - 42
ER  - 
TY  - JOUR
A1  - Ojha, Animesh K.
A1  - Forster, Stefan
A1  - Kumar, Sumeet
A1  - Vats, Siddharth
A1  - Negi, Sangeeta
A1  - Fischer, Ingo
T1  - Synthesis of well–dispersed silver nanorods of different aspect ratios and their antimicrobial properties against gram positive and negative bacterial strains
JF  - Journal of Nanobiotechnology
N2  - In the present contribution, we describe the synthesis of highly dispersed silver nanorods (NRs) of different aspect ratios using a chemical route. The shape and size of the synthesized NRs were characterized by Transmission Electron Microscopy (TEM) and UV-visible spectroscopy. Longitudinal and transverse absorptions bands confirm the rod type structure. The experimentally recorded UV-visible spectra of NRs solutions were fitted by using an expression of the extinction coefficient for rod like nano structures under the dipole approximation. Simulated and experimentally observed UV-visible spectra were compared to determine the aspect ratios (R) of NRs. The average values of R for NR1, NR2 and NR3 solutions are estimated to be 3.0 ± 0.1, 1.8 ± 0.1 and 1.2 ± 0.1, respectively. These values are in good agreement with those obtained by TEM micrographs. The silver NRs of known aspect ratios are used to study antimicrobial activities against B. subtilis (gram positive) and E. coli (gram negative) microbes. We observed that the NRs of intermediate aspect ratio (R = 1.8) have greater antimicrobial effect against both, B. subtilis (gram positive) and E. coli (gram negative). The NRs of aspect ratio, R = 3.0 has better antimicrobial activities against gram positive than on the gram negative.
KW  - antimicrobial activities
KW  - silver
KW  - nano rods
KW  - TEM
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-132222
VL  - 11
IS  - 42
ER  - 
TY  - JOUR
A1  - Fischer, Kathrin H.
A1  - Hemberger, Patrick
A1  - Bodi, Andras
A1  - Fischer, Ingo
T1  - Photoionisation of the tropyl radical
JF  - Beilstein Journal of Organic Chemistry
N2  - We present a study on the photoionisation of the cycloheptatrienyl (tropyl) radical, \(C_7H_7\), using tunable vacuum ultraviolet synchrotron radiation. Tropyl is generated by flash pyrolysis from bitropyl. Ions and electrons are detected in coincidence, permitting us to record mass-selected photoelectron spectra. The threshold photoelectron spectrum of tropyl, corresponding to the 
\(X^{+1}A1’ ← X^2E_2”\) transition, reveals an ionisation energy of 6.23 ± 0.02 eV, in good agreement with Rydberg extrapolations, but slightly lower than the value derived from earlier photoelectron spectra. Several vibrations can be resolved and are reassigned to the C–C stretch mode \(ν_{16}^+\) and to a combination of \(ν_{16}^+\) with the ring breathing mode \(ν_2^+\). Above 10.55 eV dissociative photoionisation of tropyl is observed, leading to the formation of \(C_5H_5^+\) and \(C_2H_2\).
KW  - threshold photoelectron spectroscopy
KW  - gas phase
KW  - dissociative photoionisation
KW  - reactive intermediates
KW  - synchrotron radiation
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-128652
VL  - 9
ER  -