scholarly journals Efficient photochemical generation of peroxycarboxylic nitric anhydrides with ultraviolet light emitting diodes

2015 ◽  
Vol 8 (1) ◽  
pp. 905-934
Author(s):  
N. D. Rider ◽  
Y. M. Taha ◽  
C. A. Odame-Ankrah ◽  
J. A. Huo ◽  
T. W. Tokarek ◽  
...  
Keyword(s):  
Ultraviolet Light ◽  
Light Emitting Diodes ◽  
Thermal Dissociation ◽  
Measurement Techniques ◽  
Light Output ◽  
Internal Standard ◽  
Chemical Mechanism ◽  
Light Emitting ◽  
Uv Led ◽  
Ultraviolet Light Emitting Diodes

Abstract. Photochemical sources of peroxycarboxylic nitric anhydrides (PANs) are utilized in many atmospheric measurement techniques for calibration or to deliver an internal standard. Conventionally, such sources rely on phosphor-coated low-pressure mercury (Hg) lamps to generate the UV light necessary to photo-dissociate a dialkyl ketone (usually acetone) in the presence of a calibrated amount of nitric oxide (NO) and oxygen (O2). In this manuscript, a photochemical PAN source in which the Hg lamp has been replaced by arrays of ultraviolet light-emitting diodes (UV-LEDs) is described. The output of the UV-LED source was analyzed by gas chromatography (PAN-GC) and thermal dissociation cavity ring-down spectroscopy (TD-CRDS). Using acetone, diethyl ketone (DIEK), diisopropyl ketone (DIPK), or di-n-propyl ketone (DNPK), respectively, the source produces peroxyacetic (PAN), peroxypropionic (PPN), peroxyisobutanoic (PiBN), or peroxy-n-butanoic nitric anhydride (PnBN) from NO in high yield (> 90%). Box model simulations with a subset of the Master Chemical Mechanism (MCM) were carried out to rationalize products yields and to identify side products. The use of UV-LED arrays offers many advantages over conventional Hg lamp setups, including greater light output over a narrower wavelength range, lower power consumption, and minimal generation of heat.

scholarly journals Efficient photochemical generation of peroxycarboxylic nitric anhydrides with ultraviolet light-emitting diodes

2015 ◽  
Vol 8 (7) ◽  
pp. 2737-2748
Author(s):  
N. D. Rider ◽  
Y. M. Taha ◽  
C. A. Odame-Ankrah ◽  
J. A. Huo ◽  
T. W. Tokarek ◽  
...  
Keyword(s):  
Ultraviolet Light ◽  
Light Emitting Diodes ◽  
Thermal Dissociation ◽  
Measurement Techniques ◽  
Internal Standard ◽  
Chemical Mechanism ◽  
High Yield ◽  
Light Emitting ◽  
Uv Led ◽  
Ultraviolet Light Emitting Diodes

Abstract. Photochemical sources of peroxycarboxylic nitric anhydrides (PANs) are utilized in many atmospheric measurement techniques for calibration or to deliver an internal standard. Conventionally, such sources rely on phosphor-coated low-pressure mercury (Hg) lamps to generate the UV light necessary to photo-dissociate a dialkyl ketone (usually acetone) in the presence of a calibrated amount of nitric oxide (NO) and oxygen (O2). In this manuscript, a photochemical PAN source in which the Hg lamp has been replaced by arrays of ultraviolet light-emitting diodes (UV-LEDs) is described. The output of the UV-LED source was analyzed by gas chromatography (PAN-GC) and thermal dissociation cavity ring-down spectroscopy (TD-CRDS). Using acetone, diethyl ketone (DIEK), diisopropyl ketone (DIPK), or di-n-propyl ketone (DNPK), respectively, the source produces peroxyacetic (PAN), peroxypropionic (PPN), peroxyisobutanoic (PiBN), or peroxy-n-butanoic nitric anhydride (PnBN) from NO in high yield (> 90 %). Box model simulations with a subset of the Master Chemical Mechanism (MCM) were carried out to rationalize product yields and to identify side products. The present work demonstrates that UV-LED arrays are a viable alternative to current Hg lamp setups.

ACCURATE MEASUREMENT OF ULTRAVIOLET LIGHT-EMITTING DIODES

2021 ◽  
Author(s):  
C. Yuqin Zong ◽  
Cameron Miller
Keyword(s):  
Ultraviolet Light ◽  
Light Emitting Diodes ◽  
Luminous Flux ◽  
Junction Temperature ◽  
Integrating Sphere ◽  
Light Emitting ◽  
Type D ◽  
Uv Led ◽  
Uv Leds ◽  
Ultraviolet Light Emitting Diodes

We have developed a new calibration capability for 200 nm to 400 nm ultraviolet light-emitting diodes (UV LEDs) using a Type D gonio-spectroradiometer. The recently-introduced mean differential continuous pulse (M-DCP) method is used to overcome the measurement difficulty associated with the initial forward voltage, VF, anomaly of a UV LED, which makes it impossible to use VF to infer junction temperature, TJ, during pulsed operation. The new measurement facility was validated indirectly by comparing the measured total luminous flux of a white LED with that measured using the NIST’s 2.5 m absolute integrating sphere. The expanded calibration uncertainty for the total radiant flux is approximately 2 % to 3 % (k = 2) depending the wavelength of the UV LED.

scholarly journals Improving Optical Performance of Ultraviolet Light-Emitting Diodes by Incorporating Boron Nitride Nanoparticles

Electronics ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 835 ◽  
Author(s):  
Caiman Yan ◽  
Qiliang Zhao ◽  
Jiasheng Li ◽  
Xinrui Ding ◽  
Yong Tang ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Ultraviolet Light ◽  
Light Emitting Diodes ◽  
Light Output ◽  
Light Emitting ◽  
Air Interface ◽  
Red Led ◽  
Boron Nitride Nanoparticles ◽  
Optical Flux ◽  
Ultraviolet Light Emitting Diodes

Ultraviolet light-emitting diodes (UVLED) are a new type of device in the LED development; however, the radiant efficacy of UVLEDs is still too low to satisfy the requirements of applications. In this study, boron nitride nanoparticles (BN NPs) are incorporated into the UVLED’s silicone encapsulation to improve the optical output power. This BN NPs-based package shows an increase in optical flux of 8.1% compared with silicone-only encapsulation when the BN NP concentration is optimized at 0.025 wt%. By analyzing the BN NP film, adding the BN NPs into silicone leads to a decrease in transmittance but an increase in haze. Haze and transmittance has an excellent negative correlation with increasing BN concentration under 365 nm. The moderate BN NP concentration maximizes the scattering performance from haze while maintaining high transmittance. Therefore, this enhanced light output is attributed to scattering that reduces optical losses from total internal reflection at the silicone–air interface. By using the new BN-based structure in green and red quantum dot devices, an increase radiant flux of the device is observed, 9.9% for green LED and 11.4% for red LED. This indicates that BN NPs have potential prospects in the application of UV LEDs used as excitation sources for quantum dots.

scholarly journals Nanostructural Effect of ZnO on Light Extraction Efficiency of Near-Ultraviolet Light-Emitting Diodes

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Young Jae Park ◽  
Hyounsuk Song ◽  
Kang Bok Ko ◽  
Beo Deul Ryu ◽  
Tran Viet Cuong ◽  
...  
Keyword(s):  
Ultraviolet Light ◽  
Indium Tin Oxide ◽  
Light Emitting Diodes ◽  
Light Output ◽  
Light Extraction Efficiency ◽  
Zno Nanostructures ◽  
Light Emitting ◽  
Near Ultraviolet ◽  
Output Efficiency ◽  
Ultraviolet Light Emitting Diodes

The effect of ZnO nanostructures on the light output power of 375 nm near-ultraviolet light-emitting diodes (NUV-LEDs) was investigated by comparing one-dimensional (1D) nanorods (NR-ZnO) with two-dimensional (2D) nanosheets (NS-ZnO). ZnO nanostructures were grown on a planar indium tin oxide (ITO) by solution based method at low temperature of 90°C without degradation of the forward voltage. At an injection current of 100 mA, the light output efficiency of NUV-LED with NR-ZnO was enhanced by around 30% compared to the conventional NUV-LEDs without ZnO nanostructures. This improvement is due to the formation of a surface texturing, resulting in a larger escape cone and a multiple scattering for the photons in the NUV-LED, whereas the light output efficiency of NUV-LED with NS-ZnO was lower than that of the conventional NUV-LEDs due to the internal reflection and light absorption in the defective sites of NS-ZnO.

Sign in / Sign up

Export Citation Format

Share Document