scholarly journals Modeling the infrared cascade spectra of small PAHs: the 11.2 μm band

2021 ◽  
Vol 140 (9) ◽  
Author(s):  
Cameron J. Mackie ◽  
Alessandra Candian ◽  
Timothy J. Lee ◽  
Alexander G. G. M. Tielens

AbstractThe profile of the 11.2 μm feature of the infrared (IR) cascade emission spectra of polycyclic aromatic hydrocarbon (PAH) molecules is investigated using a vibrational anharmonic method. Several factors are found to affect the profile including: the energy of the initially absorbed ultraviolet (UV) photon, the density of vibrational states, the anharmonic nature of the vibrational modes, the relative intensities of the vibrational modes, the rotational temperature of the molecule, and blending with nearby features. Each of these factors is explored independently and influence either the red or blue wing of the 11.2 μm feature. The majority impact solely the red wing, with the only factor altering the blue wing being the rotational temperature.

2019 ◽  
Author(s):  
Yachu Du ◽  
Kyle Plunkett

We show that polycyclic aromatic hydrocarbon (PAH) chromophores that are linked between two five-membered rings can access planarized structures with reduced optical gaps and redox potentials. Two aceanthrylene chromophores were connected into dimer model systems with the chromophores either projected outward (2,2’-biaceanthrylene) or inward (1,1’-biaceanthrylene) and the optical and electronic properties were compared. Only the planar 2,2’-biaceanthrylene system showed significant reductions of the optical gaps (1 eV) and redox potentials in relation to the aceanthrylene monomer.<br>


2019 ◽  
Author(s):  
Yachu Du ◽  
Kyle Plunkett

We show that polycyclic aromatic hydrocarbon (PAH) chromophores that are linked between two five-membered rings can access planarized structures with reduced optical gaps and redox potentials. Two aceanthrylene chromophores were connected into dimer model systems with the chromophores either projected outward (2,2’-biaceanthrylene) or inward (1,1’-biaceanthrylene) and the optical and electronic properties were compared. Only the planar 2,2’-biaceanthrylene system showed significant reductions of the optical gaps (1 eV) and redox potentials in relation to the aceanthrylene monomer.<br>


2016 ◽  
Vol 9 (1) ◽  
pp. 64-72
Author(s):  
Fauziati Fauziati ◽  
Eldha Sampepana

Palm shell liquid smoke obtained by pyrolysis and redestilasi still produce a pungent smoke flavor and color of yellow to brownish yellow so that the necessary research purification of smoke that can be used as ingredients other than preservatives, such as antiseptic hand wash. The research objective is to reduce the stinging liquid smoke aroma, color is tawny and to identify the characterization of the active components of liquid smoke shell oil refining results in Gas Chromatography Mass Spectrometry (GC-MS). The purification process of liquid smoke with redistilled at a temperature of 2000C and by adding 4.5% zeolite adsorbent made three (3) times the resulting liquid smoke of distillate and residue. Liquid smoke produced from distillate and residue are added activated charcoal as much as 9%, 10.5% and 12%, then stirred with a shaker subsequently allowed to stand for 6 days and 10 days The results of the study showed that liquid smoke purification results of the residue by the addition of activated charcoal as 12% and the time saved for 10 days (A2B2C3) gives flavor and color by 1.94 of 1.84 is odorless, yellowish white color and clarity. While the characteristics of the active components of purification results are predominantly acetic acid and phenol compounds of residues that serve as preservatives, antibacterial and antioxidant compounds while PAH (Polycyclic Aromatic Hydrocarbon), namely tar, benzoperen, gualakol and siringoll (aroma causes) undetectedABSTRAKAsap cair cangkang sawit yang diperoleh melalui proses pirolisis dan redestilasi masih menghasilkan aroma asap menyengat dan warna kuning hingga kuning kecoklatan sehingga diperlukan penelitian pemurnian asap yang dapat digunakan sebagai bahan lain selain pengawet, seperti antiseptik pencuci tangan. Tujuan penelitian adalah  untuk mengurangi aroma asap cair yang menyengat, warna yang masih kuning kecoklatan dan untuk  mengidentifikasi karakterisasi komponen aktif asap cair cangkang sawit hasil pemurnian secara Kromatografi Gas Spektrometri Massa (GC-MS). Proses  pemurnian asap cair dengan  redistilasi pada suhu 2000C dan dengan menambahkan adsorben zeolit 4,5% yang dilakukan sebanyak 3 (tiga) kali  dihasilkan asap cair dari Destilat dan Residu . Asap cair  yang dihasilkan dari destilat dan residu ditambahkan arang aktif sebanyak 9%,10,5% dan 12%  kemudian diaduk dengan shaker selanjutnya didiamkan selama 6 hari dan 10 hari .Hasil penelitian menunjukkan bahwa asap cair hasil pemurnian dari residu dengan penambahan arang aktif sebanyak 12% dan waktu simpan selama 10 hari ( A2B2C3 ) memberikan aroma sebesar 1,94 dan warna sebesar 1,84 adalah tidak berbau ,  warna putih kekuningan dan jernih . Sedangkan  karakteristik  komponen aktif hasil pemurnian yang paling dominan  adalah  senyawa acetic acid dan phenol  dari residu yang berfungsi sebagai bahan pengawet, antibakteri dan antioksidan sedangkan senyawa PAH (Polycyclic Aromatic Hydrocarbon) yaitu tar, benzoperen,  gualakol  dan siringoll ( penyebab aroma ) tidak terdeteksi . Kata kunci : asap cair, cangkang sawit, komponen aktif, pemurnian, redestilasi 


2015 ◽  
Vol 14 (5) ◽  
pp. 1195-1202 ◽  
Author(s):  
Nadia Crini ◽  
Coline Druart ◽  
Caroline Amiot ◽  
Sophie Gavoille ◽  
Gregorio Crini

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