Jerzy Sepioł - Academia.edu (original) (raw)

Papers by Jerzy Sepioł

ChemInform, Aug 20, 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Proceedings of SPIE, May 31, 2002

In this work we report the spectroscopic observation of single organic molecules in solid-deposit... more In this work we report the spectroscopic observation of single organic molecules in solid-deposited matrices using a confocal microscope at liquid-helium temperature. The fluorescence microscopy allowed to study the spectroscopic properties of many single molecules in parallel Matrix ...

Journal of Molecular Structure, Nov 1, 2018

5-bis(2′-benzoxazolyl)hydroquinone (BBHQ), a dually fluorescent ESIPT system revisited: XRD analy... more 5-bis(2′-benzoxazolyl)hydroquinone (BBHQ), a dually fluorescent ESIPT system revisited: XRD analysis and supersonic jet studies of deuterated species,

Physical Chemistry Chemical Physics, 2017

We describe various experimental approaches that have been used to obtain a detailed understandin... more We describe various experimental approaches that have been used to obtain a detailed understanding of double hydrogen transfer in porphycene, a model system for intramolecular hydrogen bonding and tautomerism. The emerging picture is that of a multidimensional tautomerization coordinate, with several vibrational modes acting as reaction-promoters or inhibitors through anharmonic intermode coupling. Tunnelling processes, coherent in the case of isolated molecules and incoherent in condensed phases, are found to play a major role even at elevated temperatures. Single-molecule spectroscopy studies reveal large fluctuations in hydrogen transfer rates observed over time for the same chromophore. Scanning probe microscopy is employed to directly observe the structure and tautomerization dynamics of single molecules adsorbed on metal surfaces and demonstrates how the interactions of the molecules with atoms of the supporting surface affect their static and dynamic properties: different tautomeric forms are stabilized for molecules depending on the surface structure and the reaction mechanism can also change, from a concerted to a stepwise transfer. The scanning probe microscopy studies prove that tautomerization in single molecules can be induced by different stimuli: heat, electron attachment, light, and force exerted by the microscope's tip. Possible applications utilizing tautomerism are discussed in combination with molecular architectures on surfaces, which could pave the way for the development of single-molecule electronics.

Journal of Molecular Structure, Jun 1, 2021

Abstract New near-infrared broad-band emission with λmax~920 nm was detected in 2,5-bis(2′-benzox... more Abstract New near-infrared broad-band emission with λmax~920 nm was detected in 2,5-bis(2′-benzoxazolyl)hydroquinone (BBHQ), a molecule known to undergo the single proton transfer in the ESIPT reaction and to emit the fluorescence with λmax ~600 nm. The new emission was attributed to the fluorescence of the product of double proton transfer in the excited BBHQ. The attribution was based on the qualitative agreement verifying the theoretical predictions and on the behaviour of the two properly chosen derivatives: the diethyl-BBHQ independently showing the same broad-band IR fluorescence, and the monomethoxy-BBHQ, a “negative witness”- a structure with one of two ESIPT reactivity sites eliminated, showing no trace of the new emission.

Journal of Physics E: Scientific Instruments, Apr 1, 1981

A nanosecond laser spectrophotometer with a tunable dye laser probe pulse continuously delayed up... more A nanosecond laser spectrophotometer with a tunable dye laser probe pulse continuously delayed up to about 100 ns with respect to the nitrogen laser pump pulse is described. A time scale synchronisation method for reconstruction of the time-resolved transient absorption spectra is employed. Transient spectra of anthracene in acetonitrile from 415 to 630 nm are given as examples.

In 1989 Moerner and Kador succeeded in detecting single molecules in absorption with a sophistica... more In 1989 Moerner and Kador succeeded in detecting single molecules in absorption with a sophisticated double modulation technique [1]. A much better signal to background ratio was obtained by Orrit and Bernard [2] using the method of fluorescence excitation. Single molecule spectroscopy allows to study the distribution of molecular properties and not only the statistical average which is generally observed. Wild, Güttler, Pirotta and Renn have investigated the linear as well as the quadratic Stark effect of pentacene in a p-terphenyl crystal [3]. Results on the linear Stark effect in a polymer were obtained by Orrit et al. Some of their investigated terrylene molecules showed a surprisingly strong induced dipole moment [4].

The Journal of Physical Chemistry, Dec 1, 1992

The bichromophoric molecule, bis(9-anthryloxy)methane, in which two anthracene rings are connecte... more The bichromophoric molecule, bis(9-anthryloxy)methane, in which two anthracene rings are connected by the highly flexible O-CH 2 -O link has been prepared and was shown to undergo very efficient photocyclomerization in the singlet state (Φ R =0.36) compared to other bisanthracenes. The S 0 -S 1 transition has been studied both in solution, using absorption and fluorescence spectroscopies, and in a supenonic free jet, using fluorescence excitation and dispersed emission spectroscopy

ChemInform, Aug 22, 2010

Acta Physica Polonica A, Dec 1, 2007

The spatial distributions of individual dibenzanthanthrene electronic transition dipole moments i... more The spatial distributions of individual dibenzanthanthrene electronic transition dipole moments in solid Xe was investigated at the single molecule level, with the high-resolution fluorescence spectroscopy. Samples were prepared by the co-deposition of dibenzanthanthrene/Xe vapours onto the 50 K surface. The results indicate that the orientation of planar aromatic molecules is preferentially parallel to the trapping surface.

Polish Journal of Chemistry, 2009

... ence, An kara Uni ver sity, Tando ( gan 06100, An kara, Tur key *Tel.: +420-58-5634355; e-mai... more ... ence, An kara Uni ver sity, Tando ( gan 06100, An kara, Tur key *Tel.: +420-58-5634355; e-mail: katerina.kutlakova@email.cz (Re ceived Au gust 28th, 2008; re vised manu script June 10th, 2009) The fol low ing com plexes ...

Visible emission bands coming from UV-irradiated cyanoacetylene isolated in frozen inert gas soli... more Visible emission bands coming from UV-irradiated cyanoacetylene isolated in frozen inert gas solids (Ar, Kr, N2) were discovered and tentatively assigned to the C3N radical.

Journal of Physical Chemistry A, Aug 13, 2013

Chemical Physics, Dec 1, 2002

ABSTRACT

Journal of Chemical Physics, Jul 21, 2011

Excited-state intramolecular proton transfer (ESIPT) reaction has been studied in a molecule show... more Excited-state intramolecular proton transfer (ESIPT) reaction has been studied in a molecule showing dual fluorescence, the 2,5-bis(2-benzoxazolyl)-4-methoxyphenol (BBMP), and its isotopomers, where the methoxy, and alternatively, the OH group has been deuterated. Attention is focused on the influence of electron donating OCH3 substituent on fast excited state reaction. Comparison between the resonance-enhanced multiphoton ionization spectrum and the laser-induced excitation of the primary and phototautomeric emissions has been done. The geometry, electron density distribution, vibrational structure as well as the potential energy profiles in the S0 and S1 states of four possible rotameric forms of BBMP were calculated with application of the density functional theory (DFT). It allowed identifying the most probable conformer and assessing the role of low-frequency motions for the ESIPT efficiency.

Polish Journal of Chemistry, 2008

A product ofcyanoacetylene photodissociation in Kr matrices gives rise to visible emission bands ... more A product ofcyanoacetylene photodissociation in Kr matrices gives rise to visible emission bands tentatively identified as due to the fluorescence and to the phosphorescence of the C 3 N° radical. This assignment, which involves the low-lying A 2 Π state as the final one for both emissions, is based on the isotopic substitution study and on former theoretical predictions.

ChemInform, 2010

Review of Scientific Instruments, 1994

A computer controlled apparatus for laser flash spectroscopy has been constructed. Nitrogen laser... more A computer controlled apparatus for laser flash spectroscopy has been constructed. Nitrogen laser (energy 1 mJ, pulse width 1 ns) is used both for excitation of the sample and for pumping a tunable dye laser which serves as a source of monitoring light. Two different scan modes are possible: (i) a scan with a fixed wavelength of the monitoring light: the temporal evolution of the transient absorption in the range from −2 up to 100 ns can be observed by changing the length of the variable self-compensating optical delay line, or (ii) a scan with a fixed time delay: the corresponding transient absorption in the range 380–800 nm can be measured. For illustration, the transient absorption spectrum of benzophenone in methylcyclohexane, decay curves of the singlet state of benzanthracene in ethanol in the presence of a quencher, and a ‘‘negative absorption’’ of rhodamine B in nitriles are reported.