5 research outputs found
A flattening in the Optical Light Curve of SN 2002ap
We present the broad band optical photometry of the Type Ic
supernova SN 2002ap obtained during 2002 February 06 -- March 23 in the early
decline phases and also later on 2002 15 August. Combining these data with the
published ones, the general light curve development is studied. The time and
luminosity of the peak brightness and the peak width are estimated. There is a
flattening in the optical light curve about 30 days after the maximum. The
flux decline rates before flattening are 0.1270.005, 0.0820.001,
0.0740.001, 0.0620.001 and 0.0400.001 mag day in ,
, , and passbands respectively, while the corresponding
values after flattening are about 0.02 mag day in all the passbands. The
maximum brightness of SN 2002ap mag, is comparable to that of
the type Ic 1997ef, but fainter than that of the type Ic hypernova SN 1998bw.
The peak luminosity indicates an ejection of 0.06 M
Ni mass.
We also present low-resolution optical spectra obtained during the early
phases.
The SiII absorption minimum indicates that the photospheric velocity
decreased from
21,360 km s to 10,740 km s during a period of 6
days.Comment: 7 pages, 5 figures, Submitted to MNRA
Photochemical Study of [33](1,3,5)Cyclophane and Emission Spectral Properties of [3n]Cyclophanes (n = 2-6)
Thephotochemical reaction of [33](1,3,5)cyclophane 2, which is a photoprecursor for the formation of propella[33]prismane 18, was studied using a sterilizing lamp (254 nm). Upon photolysis in dry and wet CH2Cl2 or MeOH in the presence of 2 mol/L aqueous HCl solution, the cyclophane 2 afforded novel cage compounds comprised of new skeletons, tetracyclo[6.3.1.0.2,704,11]dodeca-5,9-diene 43, hexacyclo[6.4.0.0.2,60.4,110.5,1009,12]dodecane 44, and pentacyclo[6.4.0.0.2,60.4,1105,10]dodecane 45. All of these products were confirmed by the X-ray structural analyses. A possible mechanism for the formation of these photoproducts via the hexaprismane derivative 18 is proposed. The photophysical properties in the excited state of the [3n]cyclophanes ([3n]CP, n = 2-6) were investigated by measuring the emission spectra and determining the quantum yields and lifetimes of the fluorescence. All [3n]CPs show excimeric fluorescence without a monomeric one. The lifetime of the excimer fluorescence becomes gradually longer with the increasing number of the trimethylene bridges. The [3n]CPs also shows excimeric phosphorescence spectra without vibrational structures for n = 2, 4, and 5, while phosphorescence is absent for n = 3 and 6. With an increase in symmetry of the benzene skeleton in the [33]- and [36]CPs, the probability of the radiation (phosphorescence) process from the lowest triplet state may drastically decrease