51 research outputs found
Problematika Permohonan Grasi Menurut Undang-undang Nomor 22 Tahun 2002
According to executor attorney opinion, no time limit for application clemency, it wills be performing deep constraint on dead punishment execution. Execution of dead punishment also constraint by rule that allows criminal to propose the second clemency application. This constraint still is added by condition that second clemency application is two years of first clemency rejection. Meanwhile according to criminal lawyer reception, with no rule upon, constitute a advantage by criminal dead, since it can propose clemency without time limit for first clemency application and also second application, so execution could be delayed. At Yogyakarta court since year 2002 until now there is no criminal propose clemencies. It is caused, firstly, certain verdict type that could be requested for clemency, secondary by apply clemency cause dead sentence is no postpone except for dead verdict, thirdly most criminal on narcotic and drug abuse case was pleased with first grade verdict
Rigid, Branched Porphyrin Antennas: Control over Cascades of Unidirectional Energy Funneling and Charge Transfer
Porphyrin
arrays consisting of three peripheral Zinc porphyrins
(ZnPs) and a central free base porphyrin (H<sub>2</sub>P)īøall
rigidly linked to each otherīøserve as light-harvesting antennas
as well as electron donors and are flexibly coupled to an electron-accepting
C<sub>60</sub> to realize the unidirectional flow of (i) excited-state
energy from the ZnPs at the periphery to the H<sub>2</sub>P, (ii)
electrons to C<sub>60</sub>, and (iii) holes to H<sub>2</sub>P and,
subsequently, to ZnP. Dynamics following photoexcitation are elucidated
by time-resolved transient absorption measurements on the femto-,
pico-, nano-, and microsecond time scales and are examined by multiwavelength
as well as target analyses. Hereby, full control over the charge shift
between H<sub>2</sub>P and ZnP to convert the (ZnP)<sub>3</sub>āH<sub>2</sub>P<sup>ā¢+</sup>āC<sub>60</sub><sup>ā¢ā</sup> charge-separated state into (ZnP)<sub>3</sub><sup>ā¢+</sup>āH<sub>2</sub>PāC<sub>60</sub><sup>ā¢ā</sup> charge-separated state is enabled by the solvent polarity: It is
deactivated/switched-off in apolar toluene, while in polar benzonitrile
it is activated/switched-on. Activating/switching impacts the recovery
of the ground state via charge recombination rates, which differ by
up to 2 orders of magnitude. All charge-separated states lead to the
repopulation of the ground state with dynamics that are placed in
the inverted region of the Marcus parabola
Charge Transfer Events in Semiconducting Single-Wall Carbon Nanotubes
Electron-donating ferrocene units have been attached to SWNTs, with different degrees of functionalization. By means of a complementary series of novel spectroscopic techniques (i.e., steady-state and time-resolved), we have documented that mutual interactions between semiconducting SWNT and the covalently attached electron donor (i.e., ferrocene) lead, in the event of photoexcitation, to the formation of radical ion pairs. In the accordingly formed radical ion pairs, oxidation of ferrocene and reduction of SWNT were confirmed by spectroelectrochemistry. It is, however, shown that only a few semiconducting SWNTs [i.e., (9,4), (8,6), (8,7), and (9,7)] are susceptible to photoinduced electron transfer processes. These results are of relevant importance for the development of SWNT-based photovoltaics
Theoretical and Experimental Insights into the Surface Chemistry of Semiconductor Quantum Dots
We present a series of non-stoichiometric
cadmium sulfide quantum-dot (QD) models. Using density functional
theory (DFT) and semi-empirical molecular orbital (MO) calculations,
we explore the ligand binding and exchange chemistry of these models.
Their surface morphology allows for these processes to be rationalized
on the atomic scale. This is corroborated by ultravioletāvisible
(UVāvis), infrared (IR), and inductively coupled plasmaāoptical
emission spectroscopy (ICPāOES)
Iodine-Pseudohalogen Ionic Liquid-Based Electrolytes for <i>Quasi</i>-Solid-State Dye-Sensitized Solar Cells
In the current work,
novel symmetrically alkyl-substituted imidazolium-based ionic liquids
have been synthesized featuring either iodide (I<sup>ā</sup>) or selenocyanate (SeCN<sup>ā</sup>) as counteranions. Physicochemical
assays based on spectroscopy and electrochemistry techniques have
been performed to identify the best ionic liquid for application as
electrolytes in <i>quasi</i>-solid-state dye-sensitized
solar cells (qssDSSC). The latter were mixed with additives such as
4-<i>tert</i>-butylpyridine (4tbpy) and guanidinium thiocyanate
(GuSCN) to optimize electrode surface coverage, ionic diffusion, and
dye regeneration. In addition, we demonstrate that electrolytes containing
a mixture of I<sub>2</sub> and (SeCN)<sub>2</sub> enhance the open-circuit
voltage of the final <i>quasi</i>-solid-state device by
up to 70 mV. As such, iodine-pseudohalogen electrolytes reveal in
qssDSSCs a good balance between dye regeneration and hole transport
and, in turn, enhance the overall solar energy conversion efficiency
by 70% with respect to reference qssDSSCs with iodine-based electrolytes.
Finally, devices with the iodine-pseudohalogen electrolyte show a
1000 h stable efficiency of 7ā8% under outdoor temperature
operation conditions and 1 sun illumination
Theoretical and Experimental Insights into the Surface Chemistry of Semiconductor Quantum Dots
We present a series of non-stoichiometric
cadmium sulfide quantum-dot (QD) models. Using density functional
theory (DFT) and semi-empirical molecular orbital (MO) calculations,
we explore the ligand binding and exchange chemistry of these models.
Their surface morphology allows for these processes to be rationalized
on the atomic scale. This is corroborated by ultravioletāvisible
(UVāvis), infrared (IR), and inductively coupled plasmaāoptical
emission spectroscopy (ICPāOES)
Polyhydrogenated Graphene: Excited State Dynamics in Photo- and Electroactive Two-Dimensional Domains
Understanding
the phenomenon of intense photoluminescence in carbon
materials such as hydrogenated graphene, graphene nanoribbons, and
so forth is at the forefront of investigations. In this study, six
different types of hydrogenated graphene (phG) produced from different
starting materials were fully characterized in terms of structure
and optical spectroscopy. Comprehensive photoluminescence lifetime
analyses of phGs were conducted by combining time-correlated single-photon
counting with steady-state fluorescence spectroscopy and femtosecond
transient absorption spectroscopy. The conclusion drawn from these
assays is that graphene islands with diameters in the range from 1.1
to 1.75 nm reveal band gap photoluminescence between 450 and 800 nm.
As a complement, phGs were implemented in hybrids with water-soluble
electron accepting perylenediimides (PDIs). By virtue of mutual Ļ-stacking
and charge transfer interactions with graphene islands, PDIs assisted
in stabilizing aqueous dispersion of phG. Implicit in these ground
state interactions is the formation of 300 ps lived charge separated
states once photoexcited
Quantum-Dot-Sensitized Solar Cells: Understanding Linker Molecules through Theory and Experiment
We have investigated the role of linker molecules in
quantum-dot-sensitized
solar cells (QDSSCs) using density-functional theory (DFT) and experiments.
Linkers not only govern the number
of attached QDs but also influence charge separation, recombination,
and transport. Understanding their behavior is therefore not straightforward.
DFT calculations show that mercaptopropionic acid (MPA) and cysteine
(Cys) exhibit characteristic binding configurations on TiO<sub>2</sub> surfaces. This information is used to optimize the cell assembly
process, yielding Cys-based cells that significantly outperform MPA
cells, and reach power conversion efficiencies (PCE) as high as 2.7%
under AM 1.5 illumination. Importantly, the structural information
from theory also helps understand the cause for this improved performance
A Metallofullerene Electron Donor that Powers an Efficient Spin Flip in a Linear Electron DonorāAcceptor Conjugate
The dream target of artificial photosynthesis
is the realization
of long-lived radical ion pair states that power catalytic centers
and, consequently, the production of solar fuels. Notably, magnetic
field effects, especially internal magnetic field effects, are rarely
employed in this context. Here, we report on a linear Lu<sub>3</sub>N@<i>I</i><sub><i>h</i></sub>-C<sub>80</sub>āPDI
electron donorāacceptor conjugate, in which the presence of
the Lu<sub>3</sub>N cluster exerts an appreciable electron nuclear
hyperfine coupling on the charge transfer dynamics. As such, a fairly
efficient radical ion pair intersystem crossing converts the initially
formed singlet radical ion pair state, <sup>1</sup>[(Lu<sub>3</sub>N@<i>I</i><sub><i>h</i></sub>-C<sub>80</sub>)<sup>ā¢+</sup>āPDI<sup>ā¢ā</sup>], to the corresponding
triplet radical ion pair state, <sup>3</sup>[(Lu<sub>3</sub>N@<i>I</i><sub><i>h</i></sub>-C<sub>80</sub>)<sup>ā¢+</sup>āPDI<sup>ā¢ā</sup>]. Most notably, the radical
ion pair state lifetime of the latter is nearly 1000 times longer
than that of the former
Enhancing Molecular Recognition in Electron DonorāAcceptor Hybrids via Cooperativity
Herein, we report
the synthesis of guanidinium bis-porphyrin tweezers <b>1</b> and fullerene carboxylate <b>3</b>, their assembly
into a novel supramolecular <b>1@3</b> electron donorāacceptor
hybrid, and its characterization. In solution, the binding constant
affording <b>1@3</b> is exceptionally high. <b>1@3</b>, which features a highly confined topography, builds up from a combination
of guanidinium-carboxylate hydrogen bonding and ĻāĻ
stacking/charge-transfer motifs. The latter is governed by interactions
between the electron-donating porphyrin and the electron-accepting
fullerene. Importantly, positive cooperativity between the applied
binding motifs is corroborated by a number of experimental techniques,
such as NMR, absorption, fluorescence, etc. In addition, transient
absorption experiments shed light onto electron-transfer processes
taking place in the ground state and upon photoexcitation. In fact,
porphyrin excitation powers an electron transfer to the fullerene
yielding charge separated state lifetimes in the nanosecond regime
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