Gas sensing properties of phthalocyanine langmuir—blodgett films

Mukhopadhyay, S.; Hogarth, C. A.

doi:10.1002/adma.19940060216

Cited by 23 publications

(8 citation statements)

References 10 publications

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“…These properties have led to a wealth of interesting applications ranging from chemical sensors and nonlinear optical devices to inks, dyes, and photodynamic therapy . Because of their diverse applications, the optical absorption and emission properties of these molecules in solutions have been extensively studied mainly with frequency-resolved techniques, while their thin films have been investigated both spectroscopically and electrochemically . The excited states of phthalocyanines are expected to play an important role in various applications, but still little is known about the excited-state dynamics of this important class of compounds on the subnanosecond time scales …”

Section: Introductionmentioning

confidence: 99%

“…2 Because of their diverse applications, the optical absorption and emission properties of these molecules in solutions have been extensively studied mainly with frequency-resolved techniques, 3 while their thin films have been investigated both spectroscopically and electrochemically. 4 The excited states of phthalocyanines are expected to play an important role in various applications, but still little is known about the excited-state dynamics of this important class of compounds on the subnanosecond time scales. 5 Several femtosecond studies have been reported on the ultrafast excited-state dynamics of phthalocyanine films.…”

Section: Introductionmentioning

confidence: 99%

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Ultrafast Studies of Excited-State Dynamics of Phthalocyanine and Zinc Phthalocyanine Tetrasulfonate in Solution

1997

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Femtosecond measurements of transient absorption, bleach, and stimulated emission are used to study the excited-state dynamics of phthalocyanine tetrasulfonate (PcS4) and zinc phthalocyanine tetrasulfonate (ZnPcS4) in solution. In water the excited-state decay process is fast and dominated by energy relaxation due to intermolecular aggregation. In dimethyl sulfoxide (DMSO) both PcS4 and ZnPcS4 exist predominantly in the monomeric form and exhibit very different dynamics from that of the aggregates. The decays are much slower and the observed processes are strongly dependent on the probe wavelength. For PcS4 in DMSO, when probed at 790 nm, the dynamics are dominated by stimulated emission which is observed for the first time in solution. At other wavelengths either transient absorption or bleach dominates the signal. All the observed dynamics can be well fit using a double-exponential function with a fast and slow component. The fast decay has a time constant of 10 ± 4 ps for both phthalocyanines while the slow decay has a time constant of 370 ps for PcS4 and 460 ps for ZnPcS4, respectively. The overall excited-state decay dynamics correlate well with the recovery of the ground electronic state, indicating that the recovery is the predominant process on this time scale. On the basis of a simple three-state kinetic model, the fast decay (10 ps) is attributed primarily to a conversion from the second to the first excited singlet state, possibly involving vibrational relaxation in S1. There might also be a small contribution from aggregates. The first excited-state S1 subsequently decays with a time constant of 130 ps for PcS4 and 160 ps for ZnPcS4, respectively. This decay is due to a combination of radiative and nonradiative relaxation from S1 to S0 and intersystem crossing from S1 to the triplet state.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ultrafast Studies of Excited-State Dynamics of Phthalocyanine and Zinc Phthalocyanine Tetrasulfonate in Solution

1997

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“…This electron transfer can also lead to a change of the optical spectrum. As the interaction with the gases is reversible, phthalocyanines were studied as sensitive elements for conductive and optical gas sensors [ 23 , 24 , 25 , 26 , 27 ]. Another important characteristic for its use in gas detection is the remarkable chemical and thermal stability of the phthalocyanine derivatives.…”

Section: Methodsmentioning

confidence: 99%

Optical Fibre NO2 Sensor Based on Lutetium Bisphthalocyanine in a Mesoporous Silica Matrix

Debliquy

Lahem

Martinez

et al. 2018

Sensors

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In this article, we describe a NO2 sensor consisting of a coating based on lutetium bisphthalocyanine (LuPc2) in mesoporous silica. The sensor exploits the absorption spectrum change of this material which strongly and reversibly decreases in contact with NO2. NO2 is measured by following the amplitude change in the reflected spectrum of the coating deposited on the tip of a silica fibre. As diffusion of NO2 in LuPc2 is slow, the response time could be slow. To reduce it, the active molecules are dispersed in a mesoporous silica matrix deposited by a sol-gel process (Evaporation Induced Self Assembly) avoiding the formation of large crystals. Doing so, the response is fairly fast. As the recovery is slow at room temperature, the recovery time is reduced by exposure to UV light at 365 nm. This UV light is directly introduced in the fibre yielding a practical sensor sensitive to NO2 in the ppm range suitable for pollution monitoring.

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“…These organic molecules are known to be sensitive to oxidizing or reducing gases at ppm concentrations. For this reason they have been proposed as the chemically active component of both conductive and optical gas sensors [ 17 , 18 , 19 ]. Another major advantage is the remarkable chemical and thermal stability of the phthalocyanine derivatives in many environmental conditions.…”

Section: Methodsmentioning

confidence: 99%

Reversible NO2 Optical Fiber Chemical Sensor Based on LuPc2 Using Simultaneous Transmission of UV and Visible Light

Bueno

Lahem

Caucheteur

et al. 2015

Sensors

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In this paper, an NO2 optical fiber sensor is presented for pollution monitoring in road traffic applications. This sensor exploits the simultaneous transmission of visible light, as a measurement signal, and UV light, for the recovery of the NO2 sensitive materials. The sensor is based on a multimode fiber tip coated with a thin film of lutetium bisphthalocyanine (LuPc2). The simultaneous injection of UV light through the fiber is an improvement on the previously developed NO2 sensors and allows the simplification of the sensor head, rendering the external UV illumination of the film unnecessary. Coatings of different thicknesses were deposited on the optical fiber tips and the best performance was obtained for a 15 nm deposited thickness, with a sensitivity of 5.02 mV/ppm and a resolution of 0.2 ppb in the range 0–5 ppm. The response and recovery times are not dependent on thickness, meaning that NO2 does not diffuse completely in the films.

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Gas sensing properties of phthalocyanine langmuir—blodgett films

Cited by 23 publications

References 10 publications

Ultrafast Studies of Excited-State Dynamics of Phthalocyanine and Zinc Phthalocyanine Tetrasulfonate in Solution

Ultrafast Studies of Excited-State Dynamics of Phthalocyanine and Zinc Phthalocyanine Tetrasulfonate in Solution

Optical Fibre NO2 Sensor Based on Lutetium Bisphthalocyanine in a Mesoporous Silica Matrix

Reversible NO2 Optical Fiber Chemical Sensor Based on LuPc2 Using Simultaneous Transmission of UV and Visible Light

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